i think there might be weights, i forget. but balancing a perk on rarity isn't that great of an idea. really the best play would be to make the perk drop from the master of masters, since it already drops an item which lets you tinker with wands, so really it'd just be convenience.
it'd give players more reason to really explore, and have a definitive risk reward.

but i wanted to avoid stuff like that with this mod, my intention is to balance the perks via their effects, not their attainment.
no wand tinkering is the exception because there's no world where it's both fun and balanced. at least EWA/TWA/EWE/TWE (or whatever you call it) is fun to have, so it's not that much of a priority. also being a binary effect, it really limits balancing potential.

Or, just make it 2-3 times more rare than every other perk. :)

I dunno if theres weight to perks, but, instead of removing TWWE, make it either;
Locked behind Squidward
Locked behind Pyramid Boss (I don't know the name)
Or hidden in The Work , which kind of makes it a bit of a secret find that would be REALLY helpful, but only once you complete a standard Kolmii kill :)