Upon close inspection, this weapon appears to have shallow serrations along its blade.

You can activate a fleshgrinding weapon any time you deal damage with it to a living creature in melee. When this occurs, you let go of the weapon and it magically animates, grinding itself into the foe’s flesh. In each round at the start of your turn, it automatically damages that creature as if you had scored a normal hit with it (including damage from the weapon’s enhancement bonus, other weapon properties, and your normal bonus from Strength, but not extra damage from feats such as Power Attack).
The grinding continues for 5 rounds or until you or someone else pulls the fleshgrinding weapon free; doing this requires a standard action and (for anyone other than you) a successful DC 20 Strength check.
After the duration expires, a fleshgrinding weapon returns to your hand (as the returning weapon property). It will not return to your hand if the target has pulled the weapon free and still holds it.

Prerequisites: Craft Magic Arms and Armor, animate objects.
Cost to Create: 4,000 gp (plus 300 gp for base item), 320 XP, 8 days.