Disclosed is an ergonomic handle for a hand-held tool, in particular for an air tool. The handle has a trilobular shape, designed to provide a secure grip and thereby reduce operator fatigue. The handle is also flared at the end which sits nearest the workpiece. This flared feature allows the operator who presses downward on the handle while operating the tool to avoid having his hand slip past the end of the sleeve. The handle is not an integral part of the tool and can be removed to allow maintenance, repair or replacement of the tool. Moreover, in a preferred embodiment, the handle has a bore along its axis and is provided with a unique locking mechanism which prevents rotational or axial movement of the tool relative to the handle. Optionally, the outer surface of the handle is finished so as to reduce slippage in the event it becomes slick with perspiration or oil, and is made of a thermal insulating material to make use comfortable.