IMO most battlemaster maneuvers are actions that are already possible but with superiority dice as bonus on top. I'll allow all martials the same moves just without the dice bonus.
I also like the approach to just improvise and negotiate with martial players when they do special moves. I tell them: Just think in action movie moves, and we talk about what happens. Often it is something like an additional check to get an advantage like advantage on attack roll, additional damage or some conditions like prone, but if they fail something bad happens to them (the get prone themselves, loose their balance (attacks against them have advt.) or something like that.