Like the description says, Volendrung (Ref 0002e526) doesn't stay on the (deer skull) shrine after placing Shagrol's Hammer if it isn't taken immediately after DA06 shuts down. Travelling away from the area, or even reloading a save right in plain sight of the shrine causes the weapon to end up on the ground somewhere. In rare cases, it probably could end up glitching into the ground making it impossible to obtain. There probably isn't a viable solution, especially due to the way havok works in the game, but I wanted to check for sure to see if someone has any ideas.
Setting it up to work like a weapon rack is probably either too tedious or not possible. Using the Don't Havok Settle flag doesn't seem to make any difference at all, and it probably isn't a good idea anyway given that it has a tendency to make problems like this worse. Maybe the only solution here is to not forget to take it right after Malacath stops speaking.
Issue Data
Issue #33861: Volendrung doesn't stay on shrine after quest completes