Some command to clear out the items of a grave you have open or delete it entirely.

There is an option for a builder to set a flag for an NPC not to drop a grave if all it was carrying was what its original template started with (and no gold I think).
Specifically this was set up for the Pents to stop grave spam.

Is there another area that this is an issue?

In pents if you don't pick up the stuff on a grave, like SS potions etc, the mobs will just pass it on between solves. If a mob sees a grave with a soulstone it will go try to loot it, but if something else loots it before they get there it will pick up the SS graves weapon and that will be picked up every time by other mobs. So, you get tons of graves every solve unless you take the time to /ga a bunch of trash and that only fixes things for a solve or two.