Well, it allows them to use trick attack without ninjutsu, which they could use for more burst? I guess? I am not a Ninja, but this sounds like a thing that could probably be true. Hell, even if its primary use is just to protect medals, that'd totally be fine if it had a duration.
Also, I think stealth is *more* valuable in a smaller arena. Takes fking forever to get anywhere.
Completely taking away the option to use Hide seems like a bit much. I'd love to see a Hide that could be used in combat, with an ~18s duration, with increased movement speed, and... Iunno, some medium-length cooldown. Oh, and a number 16. This would be enough to give them some unique, crispy flavor. Makes it a quick engage, or an escape from almost-death. They also can't use it willy-nilly. (Or for the entirety of a match once a lead is secured.)