Most of the techniques you use in combat can be described as weapon techniques, spell techniques, or relic techniques.

More rarely, there are mech techniques, ephemeral techniques, blood techniques, and soul techniques.

The power of techniques can be affected by up to three stats: a general stat like Strength, a category stat like One-handed Melee Weapons, and a stat for how skilled you are with that individual technique.

If there's a crown over the stat for your skill with a technique, that means you can never improve it. Some techniques, usually buffs, are crowned at 1 and have no general or category stat. What you see is what you get.

A general rule: if you forget a technique by any means, then relearn it, it will be at the same level as it was when you forgot it.

There are stats like Strength and Dexterity that affect the power of techniques, but I won't directly discuss them because their in-game tutorial mostly makes sense. I will note that every individual technique only depends on one of these stats, although the stat can differ between techniques of the same type.

I will discuss how the Mech and Ephemeral classes interact with these stats.

Roles are passive abilities that can be equipped.

Most characters unlock new roles by raising their proficiency with specific techniques. (Not technique types, the individual techniques themselves.)

You can unlock more slots to equip roles to, but I have no idea how. It just happens.

If you forget a technique by removing equipment that grants it, you keep any roles you unlocked.

PoorlyDone has a very good guide to what techniques are needed for which roles.

As a Tales player, I'm having a very hard time not calling these titles.

Humanoids, meaning every class except Monster, Ephemeral Monster, and Mech, learn weapon techniques. They can be subdivided into one-handed melee, two-handed melee, one-handed ranged, two-handed ranged, and martial arts, each of which has a different stat for how good you are at using them.

Yes, I'm counting martial arts as a weapon technique. Shut up.

Characters start with at least one technique for each weapon. Using techniques teaches you more of them, e.g. repeatedly punching teaches you to kick. The game calls this "glimmering" for some reason.

Every weapon technique has a "custom" variant, except for Deflect, Parry, and the dual-wield techniques. While most techniques can potentially be learned from multiple other techniques, a "custom" technique can only be learned by using the technique it's "custom" for. For instance, Knee Split is only ever learned from Eliminate.

PoorlyDone has a guide to which techniques specifically teach which other techniques.

A rare few weapon techniques are temporarily learned when equipping a specific weapon, and lost when the weapon is removed. From PoorlyDone's guide, I think there's no way to learn these techniques permanently.

For all melee weapons and two-handed ranged weapons, the weapon techniques you learn later on can be sub-subdivided. E.g. an axe is a one-handed melee weapon, but using one can teach you moves that can only be used with an axe, not a sword. Thankfully, there's no specific axe substat--you just use the one-handed melee stat for damage.

Martial artist quirk 1: after you use any attack that involves punching your foe, you're treated as defending for the rest of the turn.

Martial artist quirk 2: using Punch can teach Kick and Tackle, but they otherwise form three separate families of moves, much like the weapon sub-subdivisions. E.g. every move you learn from Tackle can't be learned from any punching or kicking move and can't teach any punching or kicking move. Thankfully, you don't need to separately equip your arms and your legs.

There's a class called Kugutsu that can't learn or improve weapon techniques through practice, but has a chance to learn from watching other characters use techniques with the same type of weapon. The tutorial says Kugutsu must use a weapon technique on the same turn as the other character in order to learn from them, but I don't think that's true. This only applies to weapon techniques--Kugutsu learn spells normally.

Many roles can be unlocked by learning specific weapon techniques and raising your proficiency with them to level 2. None of these roles require more than two techniques. None of them require techniques from different subtypes, but they can require techniques from different sub-subtypes. (E.g. an axe technique and a longsword technique.)

There's a role for using two one-handed melee weapons in a single technique, a role for using two one-handed ranged weapons in a single technique, and a role for using one one-handed melee weapon and one one-handed ranged weapon in a single technique. Each of them requires raising two specific techniques to level 3.

Dual-wield roles don't change your existing techniques. They just let you learn new dual-wield techniques, three for each role.

Every class except Mech and Squire can learn spells.

Squires are otherwise normal humanoids with no apparent advantages.

Spell techniques can be temporarily learned from equipment, and lost when the equipment is removed. Most characters don't start with spells, so they need an item to get them started.

Although there's a stat that affects all spells, there are also five stats for specific elements.

Repeatedly casting a spell permanently teaches you other spells of the same element. You learn these spells faster if your element stat is high.

So long as you have a spell equipped via item, you will be unable to learn that spell permanently.

When your main character is Ameya, she has a different way of learning spells, but overusing it may have consequences.

Some roles unlock from raising a specific spell to level 2.

Monsters, Ephemeral Monsters, Mechs, and Relic-bearers use relic techniques.

Relic-bearers are normal humanoids, and there's no apparent trade-off for using them compared to other humanoids. They're just better.

Relics are equipment. They start out empty, but each can be filled with a relic technique if their user gets the killing blow on a monster-type enemy that uses that technique, or is part of a United Attack with someone who gets the killing blow.

From testing, I think when you get a United Attack off another United Attack--what the game calls an Overdrive--you don't get a relic technique unless the relic user strikes the final blow.

Each monster-type enemy has multiple techniques, and it seems to be random which one you learn.

If you're full up, you can "unleash" a relic technique in combat to remove it from the relic and make room for a new one.

Unleashing a conditional technique doesn't work if the condition never actually triggers. Counterattacks can be a nightmare to get rid of. EDIT: you can remove these techniques outside combat.

Monsters and Ephemeral Monsters have a permanent, unremovable relic technique to get them started. Other than that, you can't permanently learn relic techniques.

No relic techniques grant roles. This means monsters can only earn roles from spells.

Monsters and Ephemeral Monsters can't equip weapons, armor, cloaks, hats, gloves, or boots, only relics or miscellaneous accessories. This means only humanoids can learn to spellcast from weapons and armor that have spells in them. Accessories with spells in them are well worth trading or upgrading for.

Mech is the only class that uses these.

Every equippable item has a technique attached to it. Equipping it to a Mech temporarily teaches the technique.

Mech techniques cannot be learned permanently, except for one permanent technique they start with.

If Diva is your main character, then every time you recruit a character who's a Mech, you get the ability to change her chassis to match it. This changes her stats and her "permanent" technique. Chassis can be changed anytime out of combat.

Mech techniques that can attack are divided into melee and ranged, which have separate stats for your skill at using them. Mechs don't care about the one-handed or two-handed distinction.

Armor and accessories have techniques that give temporary buffs. These techniques have no associated stat.

Mechs can never permanently improve stats like Strength or Dexterity, only stats associated with techniques. However, they get additional stat bonuses from equipment.

Mechs can put any equipment in any equipment slot. There's nothing stopping you from giving them six weapons at once.

As Mechs improve their permanent technique, they keep unlocking new roles up to level 5. These are the only roles they unlock. This means Diva has a lot of roles she can only unlock when you play as her and can change her "permanent" technique.

Ephemeral Humanoids and Ephemeral Monsters use Ephemeral Techniques.

Ephemerals get temporary bonuses to stats like Strength and Dexterity as they survive more battles. These bonuses are accompanied by changes to a permanently equipped role, starting at juvenile and ending at elder.

However, role changes temporarily reduce Endurance and max Life Points. (Not HP, but the stat that goes down by 1 whenever your HP hits 0.)

When an Ephemeral's life points hit 0, they drop down to juvenile again, but get small permanent stat boosts and permanently learn some Ephemeral techniques. The higher their title was, the better the gains. Gains stack as they repeatedly fall in battle, so make sure to endanger your elders!

If you lose and retry a battle, and your Ephemeral's life points hit 0, they don't drop down to juvenile until after the battle, meaning you won't be able to use them again in this fight. Be very cautious when your plan for beating a nasty boss requires having an Ephemeral in your party.

Ephemeral techniques have no associated stat and don't unlock roles.

Siugnas the Vampire is a humanoid. I'm going for his no-Thrall ending, so most of this is from the tutorials.

By getting Thralls from events, or getting events that allow him to class-change existing characters to Thralls, he improves his blood techniques. I'm not sure if this means he gets more techniques, or the techniques get stronger.

Many events give him Thralls who aren't party members. I think this just improves his blood techniques.

The tutorial makes it sound like you can recruit Thralls by directly defeating humanoid enemies, but I haven't seen that happen.

From the tutorial, Thralls lose their preexisting "racial traits." I think this means a Relic-Bearer who becomes a Thrall can no longer use relics, as an example.

There's special equipment you can give to Thralls to turn them into Knights, which can use blood techniques.

I'm not sure whether or how Knights improve their blood techniques.

If you remove a Knight's special equipment, they permanently turn into a Wastrel, which has 1 max life point and can never learn any new techniques of any kind.

Yes, this all sounds pretty evil.

There are roles associated with blood techniques, but I don't know how they unlock.

If Mido is the main character, Kugutsu in his party learn something called soul techniques. I don't know anything about them.

Soul techniques teach quite a lot of roles.

Seriously, the guide to roles has six sections just for Kugutsu.