[Anthony]

Well, there isn't a D&D wight because the D&D wight is really a D&Dism; a 'wight' is just a creature, and a 'barrow-wight' is a draug. However, it's a monster, you don't really need rules to modify it, just assign numbers based on what you want it to do.

If you want something that functions like a D&D wight, I would have it apply an irritating condition or fatigue damage.