I don't mind arrows that deal an extra 1d6 of fire/acid/whatever. As long as they are rare and expensive or magical (Flame Arrows, 3rd level Transmutation).
I do have an issue with them being spammed by goblins or basically whoever and leaving ridiculous pools of fire or acid on the battlefield in addition to literally drenching the target. Gallons of acid from an arrow.
Goblins can make a concealed grease pool trap and light it with a normal 1d6 fire arrow that doesn't create a surface.
Acid temporarily corroding your armor is a weird concept. This is where I want things to make sense. If you want a temporary AC debuff, there are things that do make sense, like a daze effect. In D&D, there's Rust Monster that gives weapons a permanent cumulative -1 penalty. Acid corroding armor should follow the same principles and be permanent. That said, any kind of AC debuff from a cantrip on top of damage is too powerful anyway.
