A pneumatic hammer extender arm assembly is provided comprising an elongated extender arm body defining a hammer engaging portion formed at a first end of the body, and a hammerhead engaging portion formed at a second end of the body. A hammerhead is detachably engageable to the hammerhead engaging portion to allow for quick change of the hammerhead without the need for any tools. The hammerhead may alternately be implemented to engage and apply an impact force to a fastener that may be axially offset from the extender arm body.