I'd personally like to see a Gunblade. But i don't think that would happen unless the WoL went to Garlemald and someone was defecting and offering to teach them the ways of empire's fighting techniques since the gunblade is using by Garleans.

Other than that i quite like the Lulu style of fighting. Use different plushes. imagine all the different ones you could have
e.g.
Moogles
Chocobos
Cactuars
Behemoths

etc