Any suggestions what can be changed/improved? constructive criticism is welcome
Jazz imo that green doesn't fit at all, also purple and green clash. Maybe you could work over that symbol on the left a bit and add some metallic reflections with a black accents.
JihadJoe I really like your one, it's very strict and distinctive. Maybe you could work on a Sabre a bit, I mean another angle and better quality of it. I like the rest of the signature.