I would really like a shear with titanium or high grade stainless but with a solid pin and a full tang or simply all metal, no plastic handles. I have had shears fail, handles snapping off and the rivet failing as well. They are just not trustworthy.
N
If you're in an area where wire leader might be a problem, go to Ace or Home Depot and pick up a cheapy pair of wire cutters. Shears are designed for cutting fabric off a trauma victim and then get pitched in the biohazard bin. They happen to work for many cutting tasks underwater, but I wouldn't want them to be my go-to if wire leader is involved (for the reasons you mentioned). Especially since wire cutters are plentiful and inexpensive. The caveat is that wire cutters generally suck for cutting other things, like cave line or webbing, so they're pretty much a single purpose tool. Easy to drill a hole and attach a bolt snap with some cave line and keep them in a pocket.
Wire cutters $13
Twice the cost of bare trauma shears from Dive Gear Express, or 10 bucks cheaper if you get the Dive Rite shears with the harness and velcro.