I said it before, say it again - Yoda with a lightsabre is like Gandhi with a machine gun
There’s nothing in the OT to indicate Yoda was a pacifist. We may not have seen him fight, but in ESB he trained Luke in the art of defense, and in RotJ he specifically told Luke that he must confront Vader in order to become a Jedi (with Obi-Wan basically telling him not long after that he had to kill him).
I don’t have a problem with Lucas modeling prequel Yoda after the martial arts master who plays old and feeble until he’s required to kick ass. The other strong audience reaction I saw was to Yoda Force-pulling his cane and resuming his hobbled stance just before people arrived on the scene.
Interesting. I never thought of it in terms of concealing that he could still kick butt. No secret to fellow Jedi, but to everyone else?