You can charge your unarmed strike or natural weapon with additional damage potential.
Prerequisites: Str 13, Psionic Fist, base attack bonus +5.
Benefit: When you use the Psionic Fist feat, your unarmed attack or attack with a natural weapon deals an extra 4d6 points of damage instead of an extra 2d6 points.
Source: Expanded Psionics Handbook, page 47.