There's got to be some tool... perhaps one of those all-in-one style tools that opens up like a swiss army knife... I know there's some object... some tool that would open like Pong Krell's saber and lock in the open position. Something like those utility knives where you have to depress a button to then fold it again. That way it would stay rigidly open like a staff when you wanted and then close up tightly again.
I'll keep thinking I know there's got be a heavy duty style lever that would work for this off of some already-existing tool or object.