It gives you a stack of arrows as big as the one you shot from, i.e. if you have half a stack stack of tipped arrows and shoot one, you get half a stack back when you pick the arrow up. This works with all tipped arrows except the "water bottle" arrow (which gives you a normal arrow when picked up) and naming a "water bottle" arrow with an anvil does not change that.
Mikko Jutila
It gives you a stack of arrows as big as the one you shot from, i.e. if you have half a stack stack of tipped arrows and shoot one, you get half a stack back when you pick the arrow up.
This works with all tipped arrows except the "water bottle" arrow (which gives you a normal arrow when picked up) and naming a "water bottle" arrow with an anvil does not change that.