Is it possible to add similar weapon types for every other? Because they do not get weapon parts or materials, they can never hit ridiculous levels of weapon power, therefore I think the scaling for them is fine staying at 120% total, that and they require 1m to form shift to the other type of weapon.
I was thinking they would look something like..
Fire Arrows: Leaves Cinders equal to 25% of user's fire ATK for 3 rounds
Gust Arrows: Leaves air shafts for 3 rounds
Ice Arrows: Leaves ice tiles for 3 rounds.
Stone Arrows: The arrow stops at the first enemy hit, but gains 5 damage per tile traveled.
The potentials are mostly just ideas to pitch in, if you have anything better in mind then that'd be wonderful.