Took a bit, but here is the Pathfinder 2nd Edition version of the item!
Grave Spike ITEM 10
Usage held in 1 hand; Bulk 1
This heavy cold iron spike contains some of the oldest necromancy in existence.
Activate [two-actions] Make a melee attack against an undead creature that is adjacent to a surface, either vertical or horizontal. You are considered trained with this attack and the spike counts as a finesse weapon. If a hit the creature, the target must make a DC 30 Fortitude save. On a failure, the creature is impaled against the surface. The creature cannot remove the spike if it failed the original save nor can it use magic or abilities to cause another creature to remove the spike via mind control. A creature may willingly removed the spike ending the effect against the original target. On a successful save, the creature just takes 1d6 piercing damage with no other effect.
Type greater; Level 10; Price 900 gp