What's this mean?

Alduk tells you 'It is immune to purging.

That one probably shouldn't show up to mortals, but all it means is that when an Immortal "purges the room" that object will be skipped.

It's typically used for objects that are reset into rooms like pits or that have important progs attached to them. It may be on leader weapons too so Immortals don't accidentally purge those.

It shouldn't be set on ordinary gear, but it also has zero impact in terms of game mechanics either so if someone put it on a random sword it won't really hurt anything.

It's on an item from an area explore that's in a container in a room, as opposed to being carried by a mob. Was just curious.

Or just the Imm command the purges the room of objects.

It was answered on newbie recently