I love me many Kung Fu movies, where the supposed "idiot" is actually the best martial artist there.

Like in Crouching Tiger Hidden Dragon, there is a scene where the "master" puts his spear in the loop of the guys bardiche and is spinning it around to fight the lady on the other side. But really, it is the guy in the middle who is doing everything. The "master" is just loosely holding the spear.

And likewise, the guy in white above, is actually very good