Lesser Invocation; 4th
One of your hands drops off at the wrist and floats in the air. You can use the hand in all ways as if it were still attached—manipulating items, delivering attacks with a light or one-handed weapon, or even delivering a touch attack with a spell or invocation that you cast before it detaches. However, it requires you to expend the same action that would have been required—picking up an item takes a move action, making an attack takes a standard action, and so forth.
The hand flies rather than crawls, but it can't move on its own. You can move the hand up to 30 feet through the air as a move action. You can direct a disembodied hand in your space to reattach to your arm as a move action.
When you use this invocation, your current and full normal hit point totals are reduced by 5 for as long as the hand is detached. The hand is considered a Diminutive creature with AC 20 and 5 hit points. Its Hide and Move Silently modifiers are equal to your warlock level. For all other purposes, its statistics are equal to yours.
If your disembodied hand is destroyed, it regrows in 1d4 hours. At the end of this period, you regain the 5 lost hit points. Only one of your hands can be used for disembodied hand at any time; if your disembodied hand is destroyed, you can't use this invocation again until your hand regrows.
Source: Complete Mage