So the trick to killing Hammer bots with the fire sword alone is simply timing
Wait Until the hammerbot Strikes with it's hammer, Dodge it and if it did a sideways strike it will do a high strike next if it did a high strike then it'll do a sideways strike next
If it does a high strike Slice it in half by doing a sideways to counter it
If it does a side strike then jump to dodge it and do a high strike
(high strikes are using only w to strike)
(Side strikes are using a/d to strike)
Now if your fire sword Has only the first fire upgrade
Then its probaly best to play it on the safe side by letting the hammer destroy other bots and then swiftly dodging most of its attacks and then striking it in half Bababooey

Pretty simple
If they are infront of you do a side strike
If they are above you in anyway a high strike is the way to go now on the off chance they block it Simply move away and side strike again

While they are rushing towards you kick them and start swinging your sword from a high swing and hit them while their down

Move towards them and never stop strafing to either side once your close to them wait for them to shoot then dodge jump at them and side or high strike

Jump and high strike at one of his eyes