I see a lot of potential in this, so much so that I made an itch.io account just so I could post feedback about it.
The first thing I wanted to say was that switching between weapons is a bit too slow and has screwed me over a few times (swapping in the middle of combat from an armor-depleting weapon to a health-depleting one is essential for defeating most of the enemies in the demo anyway, so this could really use tinkering.) However, I think it's a nice touch that you can always melee which makes this a bit less of a problem. It is still a pretty large one either way.
Secondly I think the knight-esque looking enemy who shoots hitscanning lasers is a bit too much of a nuisance. Like the other user mentioned, he ends up hitting you regardless of mobility (mostly). A solution would be making the laser less accurate and the laser windup lower. When there's a room full of these guys I ended up depleting my armor pretty quick simply because there's lasers allover the place. It does make them a priority target and they are easy to take down, but paired with the hectic nature of the other enemies it can get a little frustrating.
I'm a huge fan of everything else though. I love the movement in the game and the armor/health type weapons system is very interesting. Good luck with this in the future