I actually have a game with very few cheats used that I'm playing for the sake of "playing". Then I have my cheat like a fool game...
I don't really want to totally ruin it for myself.
Sounds like a syntax problem. Post the exact command you're using.
Skill level only affects the enchant strength/percentage, etc. With something like night vision, it doesn't matter (same with Muffle).
Just to show the markers?