Just got a very nice might-based DPS Utility Belt with 4 wildcard slots from the T4 4-man Operation today. Its called Aggressor's Tech Canister. First 2 slots are useable, but 3rd and 4th slots need to be unlocked by spending Marks of Triumph. You need to spend 125 Marks of Triumph to unlock the 3rd wildcard slot and another 625 Marks to unlock the 4th wildcard slot. Bad news is that the Utility Belt wildcard slot unlocks are temporary and last only for 30 days. Good news is that once you unlock the 3rd slot for 1 Utility Belt, you unlock all the 3rd slots for all Utility Belts which you have. Same goes for the 4th slot. Slot unlocks are universal across all Utility Belts you own.
Edit (15-01-13): Just got the precision-based DPS Utility Belt, Precise Tech Case. Details here.