Hm. How's this for an idea. A slowed amulet of speed will rot slower, but the slow cancels out the speed. If you haste it, it rots faster, but the speed effect is also boosted.
Ah, if I remember rightly that AoGH bug is an old one. Nobody ever bothered fixing it 'cus firstly, nobody wears AoGH, and secondly, it's only the number that doesn't update, the HP actually updates. All it does is lull you into a false sense of security before killing you.
Xinroch didn't have anything special before. The artifact flaming sword was my idea in the first place. I thought gas and disease immunity on the weapon worked nicely as a theme, burning away gases and germs before it reached the player. Arcanite for the handle because the yellow would look nice with the ruby.