The [FGS] Clan

For some reason, I've been having this weird problem with lighting where like... well it's hard to explain, but there's like strange shininess to ... just about anything lit.

Is this classic installation without enb jazz, and what renderer are you having this problem with?
You are running in windowed, does this problem also occur in fullscreen?

The dock doesn't look normal to me either so initially I'd have suggested your brightness settings are messed up, you may also want to check if your renderer isn't applying gamma correction of some kind. If the problem is limited to Deus Ex then it is likely renderer issue or some bug with visuals mods. If it happens somewhere else it is prob monitor or gfx card. I recommend playing the game with Kentie's D3D10 renderer anyway, if your hardware and software supports it, alternatively Dohnal's OpenGL 2.1 (or his OGL based D3D9 if you must).

I'm using d3d10 renderer, and yes, it does it on fullscreen too.

It seemed the problem was that ClassicLighting was set to False, and that was what was making the lighting super strange.

I have the same problem Vexus, and I had to turn up the brightness to full as I couldn't see anything. I can't find a suitable render to suit my comp yet.

I believe it's just the renderer that glares it, There should be a way to lower the glariness.

I believe he already found the issue, and set ClassicLightning to True in renderer settings. Fortunately Kentie has decent documentation on his website about renderer options.