With 5 unarmed you can just melee the ants if you know what you're doing.
Check out this tutorial for how the combat works. Basically, you make sure you have a fitting block (that is, Sidestep or Watch Its Moves) set up whenever you touch the ants and you'll receive no damage. Be sure to walk away to set up your block whenever you are hit because it destroys your block.
If done right, you'll receive no damage at all. Blocks can be set up from range. Once you unlock Watch Its Move, you can have Sidestep and Watch Its Moves set at the same time to have a buffer for two attacks. Once you reach 15 AGI (apparently) your cooldown should be shorter than the ants and you can fight them without moving.
It's a lot faster than killing ants used to be in old Haven, especially once you get used to it.