in WIKI ( http://wiki.spiralknights.com/Curse ):
>>At 4 points, very high resistance, the number of weapons cursed becomes 1.
I have Skolver Coat(curse med) + Dusker Cap(curse med) = Very High curse resistance
but the number of weapons cursed still 2...
and i also known someone Maximum! curse UV same with Very High and 2 weapons cursed!!!
That article is based on observations, so you can't take the boiled down results as predictable behavior. If you read the reference link, you'll see they had trouble trying to find how the resistance scales depending on its source, and that depth could be a factor.