There are times when you just want to slow someone down, or get another chance to make your Stealth roll and hide from them. In this instance, Splinter is ideal.
Type poison, contact; Save Fortitude DC 25
Onset 1 round; Frequency 1/round for 6 rounds
Effect -1d2 Perception skill; Cure see below
This horrible crystal never looses its edge, even when ground into a powder. Splinter crystals remain needle-shaped and profoundly sharp, no matter their size. Any contact with flesh drives the material into the victim's skin.
Once in the system, the victim looses the ability to keep coherent thoughts and suffers profound hallucinations. Each minute, the victim may make a new save to wear away 1 point of the Perception penalty and fight back the visions. This is the only non-magical way to cure the poison.
Creating Splinter is exceptionally difficult and dangerous. The Craft (Alchemy) skill roll is actually DC 27. On a catastrophic failure, the alchemist will be exposed to Splinter's effects. On a normal failure, the batch's materials are wasted creating a profoundly smelly cloud of blue vapors.
(The stats above are for the Pathfinder RPG from Paizo. Adjust as needed for your preferred system.)