This is not correct, imo.
I do this:
1/3 for Wizards and 1/4 for Taoists
If a Warrior has a weapon DC 50,
Wizard 50 / 3 = 16.6, so id make there weapon MC 16.
Taoists 50 / 4 = 12.5 so i`d make there weapon SC 12 or 13.
Watch how much base SC you add to Taoists though as Curse will get silly.