PC beat me to it. Circle of Iron is one of my all time favorite movies.
From a musical standpoint, a 6 foot long "flute" (or fife) would produce indescribably low tones. A
bass flute is 146 cm (4'9") in length. Bass flutes are rarely used in modern orchestras (read: almost never) because the tone is basically inaudible, and exceedingly low. A 6 foot variety would sound most "un-flute" like, and in a crowded environment, everyone would have to basically come to a complete silence in order to hear it at all.
Furthermore, a bass flute has a curved mouthpiece so that in order to maintain proper hole distance for the fingers, the mouthpiece was curved back around so that the right hand pinky could actually reach the furthest hand.
A 6 foot long flute/staff with 6 holes, would have the furthest hole some 5 feet away from the actual blowhole. Try this: Measure the distance from your lip to your outstretched right arm's pinky finger. You'll be lucky if it's 3 feet. You can see why such a thing would be impractical.
But hey, you know what? It's a fantasy game. I say, do whatever pleases you. There's certainly no reason why such a thing couldn't be built. Like in Circle of Iron, his weapon would whistle as he batted people with it. That is certainly feasible. The fact that it's hollow should be of no concern. Bones are hollow, and they're some of the strongest things in the world.