So I started MW on my 2nd playthrough for the first time in about 7 years so I don't really remember much of the game at all. I never actually finished it or got very far the first time.

I mention this because the first night I slept in Caius Cosades house I was attacked by an assassin and I killed him took his armor and put it on.

I remember getting totally owned the first time I played this game years ago. Now however It seems very easy. Is it because I'm wearing DB armor?

Is it ok that I wear it? Do NPCs not like the fact I wear it? Is there better Light Armor because if so I haven't seen it yet.

I feel like I'm almost overpowered or something.. anyway thanks in advance.

DB armor is much better than most light armor but it shouldn't turn the game from hard to easy. Having 20 total AR instead of 10 isn't that big a deal. It's probably just that you've got a feel for the combat even if from long ago.
Npcs don't associate you wearing the armor with the DB so if you like it, wear it.

Cool thanks for that.

You probably just don't svck any more. Seven years is a long time to get better at gaming in general.