I own a WE-130 and when I clamp down on my Hinderer Spanto I get strong resistance in the locking arm even thoughI have it set on minimum tension.
Once I do get it locked down, opening the clamp requires so much effort that I have to get my wife to hold the knife steady while I use both hands to grab the base and break the lock bar tension!
Matt, the standard included jaw set are only capable to expand to 3/16". The XM-18 Spanto approaches this width at 0.16".
Another remedy to consider may be to disassemble the vise and clean out any steel dust with a clean dry towel and a can of air spray. Then sand and polish the steel surfaces of the cam lobe with very fine grit sand paper or emory cloth. I would also lubricate the steel surfaces with a dry wax lubricant.
I practice this as part of a regular maintenance program a couple times a year or sooner if needed.
From looking at my Hinderer, the blade stock does seem to be thicker than your average folder. I haven’t had a need to sharpen it yet but I’ll follow this thread to see your solution. I seem to remember other members here taking apart the vice, cleaning it and upon reassembly they did not insert the full set on belleville washers (tensioners). Now, whether or not that was a grand idea, I’ll leave up to them to expand on.
Yep, disassembling it and cleaning makes a world of difference. You wouldn’t think that it would hinder your ability to clamp down on the knife that much but it does and it’s easy to do.