Very nasty weapons

Very nasty, indeed.

reminds me of something you'd see in rival schools hehe.

That's quite an arsenal there!

WOW!!! The 'good guys' better watch out!

Tennis racket axes? How does that even work?

Presumably, you wrap your hand around the blunt part, and your enemy around the sharp part.

More seriously, I doubt the racket frame is made of the usual materials. More likely some sort of metal.

Oh it most likely isn't made out of your off the shelf components. With the enhanced strength of the brats, titanium might be just as feasible as fiberglass or shaped aluminum.

But seriously, you swing a hatchet and a racket two different ways. And both of them are designed to optimize the motion involved... the idea of slapping them together makes sense from a gimmick standpoint but it also feels like it would be a real clumsy weapon in practice. I can easily picture a GB swing one around and end up with it stuck in a telephone pole or cinderblock wall. On the other hand, I can "see" the bat, ball bombs, and ball cannon all working as suggested.

There's a lot of superhero/spy/steampunk/etc gadgets that have no business working as depicted. An axe stylized to look like a tennis racket (which is what this is, really) is a pretty minor offense against plausibility relative to some of the crazy shit out there.