Bit of an odd request and probably off theam a bit but a proto saber melee wold really turn some heads.
(A light saber variant with an external power source.)
I'm suggesting this after watching the hack Smith yt channel where there team builds a real working extendable plasma blade light saber and while he was listing all materials and component noticed all of it is already in pnc.
https://youtu.be/xC6J4T_hUKg
Could make for a pretty awesome weapon that scratches that melee itch.

Why not something like a Power Fist from the Fallout series? [1] It's canonically pneumatic even.

One dude even made their own [2]

[1] https://fallout.fandom.com/wiki/Power_fist
[2] https://www.youtube.com/watch?v=OBeP1kUJrm0

I've seen that video, and it is admittedly very cool.

If anything like that were to go into PNC, it would need to be late-game, and almost certainly require an Aerial Interface powering it to be practical. Still, maybe one day...