What are you using to track arrows? If it's an inventory item, say
Trigger:
Events
A unit is attacked
Conditions
Attacking unit equal to (your person here)
Actions
For each (Integer A) from 1 to 6, do (Actions)
Loop - Actions
If (All Conditions are True) then do (Then Actions) else do (Else Actions)
If - Conditions
(Item carried by (Attacking unit) in slot (Integer A)) Equal to (Your arrows)
Then - Actions
Item - Set charges remaining in (Item carried by (Attacking unit) in slot (Integer A)) to ((Charges remaining in (Item carried by (Attacking Unit)) in slot (IntegerA)) - 1)
That'll only work if they can only carry 1 stack of arrows. If they carry more than 1 then it'll take 1 off of each stack they carry. Not sure how to get around that shortcoming, sorry :[
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.