I would be keen on sheers replacing a knife or line cutter but for one thing, they rust up at the hinge pin and when needed fall apart, totally unreliable. The only time I recall wanting my shears I was diving with a group out of WPB I think it was. Everyone else had blown through their air leaving me and the DM remaining. We were drifting along and a turtle came circling by. It kept circling, and circling and thinking this odd as it passed close we both saw the problem, a steel leader was wrapped tightly around the turtle trapping the left pectoral fin and even cutting into it. The DM motioned to me to grab the turtle on the next pass. And I did and he was big but as soon as I grabbed him, rather than trying to escape, he just relaxed. I grabbed my shears and, yep, they fell apart. Junk. But the DM had a pair he had already pulled out and with several quick snips he had the leader gone. And as soon as the turtle felt the leader release he wanted away and I released him pronto. He zoomed off with a half circle to wave adios, maybe

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I coat my shears with 100% silicone grease including the hinge pin and even then they will quickly deteriorate. I guess there are some around that are titanium? I would just want a simple shear, not those heavy, complicated Rubic cube multi-tool things.
Zippers, I use paraffin.
Oh, a couple of years later, same outfit, I got my hair tangled in an elastic band. I asked if anybody has some shears, nope, they all had huge BFKs, not sure why everyone it seems up WPB/Jupiter way carries giant BFKs but all I wanted was a knot cut from my hair, not my head cut from my body! Yep, my shears were in two pieces again. WTH. My razor Sharp Tekna knife (mini-BFK) was used in the end to excise the knotted piece of hair.