Woah, thank you so much for the great feedback!
There are some points I would like to further ask, if you don't mind.
Thing is, isn't blinded a bit too much of a condition just to impose with an attack roll?
Yeah, that is a very good point. I thought it would be balanced around having a chance of not only fail, but also fall prone if you are too greedy with your movement. That said, I do like the idea of having some sort of mobile-acrobatic attack for monks that do not rely on Ki points. What do you think it would be better? Limit Flying Kick only to once per turn, or to require it to move first (using your regular movement), and then do the attack (like some sort of charge attack)?
Wait, let's run some numbers. At level 4 (the first time any character can access this feat), you would have +3 proficiency (+6 with Expertise), +3 Dexterity. That means between +6 to +9. Which means basically free 10 feet of movements, and up to 20 if you are feeling risky (or up to 25-30 if you are feeling particularly lucky). Nothing extremely bad, I think. At higher levels, though, that becomes anything from +11 (+6 proficiency +5 Dex) to +17, which means free 20 feet and up to 35 feet.
You know what, I think your idea of a cap is better. Simple, elegant, and allows Acrobatics to be used.
What I was targetting with this maneuver was an escape route for fragile but agile fighters after they make their attack. Like a hit-and-run (but hit-and-run by itself doesn't feel like a combat maneuver).
Yeah, it's true there are many pushing abilities. Actually, it's because I like playing with dynamic maps, things were positioning is vital. Having the non-magic people have some control options really opens up strategies (in particular because my current party is almost non-magical). Also, I wanted a stronger option than Straight Kick.
I was also confused about this ability too. I wanted to allow the tank to get some breathing room, if needed. But not sure if I made it too OP. The other option I was considering was just damage all enemies in area if their AC is lower than the attack roll (basically an AO attack), but the damage is equal to the maneuver die only. But I felt it was somehow too weak. Maybe enough for minions, but for stronger creatures, 1d4 is not going to do much.
Oh, I like this! Just one thing: isn't stun a bit too much? I feel it's one of the strongest conditions in the book, and thus why I avoided using it for the maneuvers.
This was done mostly for weapon category "balance" purposes. No particular reason you could not trip with any weapon (as the battlemaster shows). All the heavy weapons already had something going for them, so I decided to leave this to the non-heavy crowd.
Thanks a lot for all of your feedback!