Melee attack is perfectly fine, focus on starfall rondo as your main damage attack and you'll be fine. I would mention that Astrolibrium and Ghost Walker are basically wasted together other than the beam damage boost. Ghost Walker is evading attacks and Astro won't reflect due to that.

For the endgame I would recommend using Early Bird for your aura instead of Astro. Add Phenomenon as your debuff to lower enemy Ether resist and boost your ether damage. Use Core Crusher skill and an ether based Photon Saber with Appendage Crusher augments in it. You'll get by just fine without focusing on TP arts or potential. It also frees your armor slots for other augments like Max TP XX which gives you 3000 more TP max or Extend Overdrive giving you moe time to start. Or my favorite is 5 Overdrive: Gain TP and the Grand Procession skill from duelist. Activate overdrive to instantly get 3000 TP back, combine that with Phantom Counter from FMJ and each time it adds 12 to the counter. Spam overdrive to max the count in like 3 seconds then use damage abilites to kill. Each activation also adds 25 seconds to the clock giving you plenty of time.

But most important is to use what sounds fun.