Claws of darkness (KoKPG 167) is pretty decent. Sor/wiz 2nd level illusion(shadow). Get two claws as natural weapons, which are touch attacks that deal d4 cold damage. The claws deal damage on grapples, and give a fort-based slow to your opponent as long as they're grappled.
Oh, and as a free action you can switch them to giving you a 10' reach.
Unfortunately, they replace your hands, so you can't use somatic/material components or hand-slot magic items. Still, great buff for your familiar, though the range:personal makes it a little more difficult to share.
Not exactly a weapon, but shadow plate (KOKPG 185) is a fourth level sorc/wiz shadow illusion spell that grants +7 armor to AC, and absorbs CL damage before it vanishes. It'd be pretty crappy, but it lasts forever until it gets damaged, so it's a pretty good buff for off days.