Allow me to second the vote for Extrema Ratio. I picked up a Fulcrum II-D at Blade, and it's quite the tough thing. I'm sure one of ER's folders would suit your purposes extremely well, but have you considered nabbing a smaller fixed Blade instead and carrying it IWB or some similar option?
Amazing carry options have been done with the Busse Active Duty, ranging from IWB carry to some sort of nifty sheath attached to a belt loop and a belt. An excellent slicer above all, and quite the little crowbar. Then again, I'm just extremely fond of Busses.
I'd go for Extrema Ratio for tough folder. I did, actually, and I don't regret it.