or WAD?
Units with the "Never Heals" tag (i.e. the broken bone symbol) don't lose the health gained by a lifedraining weapon over time.
For example, say a non-"Never Heals" unit, like a Sleeper, wields a Wraith Sword, and ends a battle with 50 HP. Since his base HP is 26, he'll slowly lose HP each turn until he arrives back at 26.
BUT, if a GoR'd gargoyle wields a Wraith Sword, and ends a battle with 100 HP, he won't lose those HP as time passes. 10 turns later, he'll still have 100 HP (assuming he stays out of combat, etc).
Presumably this is because HP-overload-loss is included in the same "HP Reckoning" calculation that heals wounded units at the end of each turn, and "Never Heals" units are excluded from that calculation.
As an interesting side note, if the above Gargoyle is located in a province with a lab, it WILL lose HP as expected...this is because it's a magic being that heals only when a lab is present...thus it's included in the HP Reckoning, and there you go.