The proper cutting tool depends on what you want to cut/do with the tool. baed on my experience...
1) clean fish best a fish cleaner tool and thin blade knife. A dive knife (particularlly with serations on the back) makes a good second choice.
2) spreading stuff on bread at lunch time, a kitchen knife works well,as does a spoon. In a pinch a dive knife works.
3) cutting nylon, polypro, cotton fishing/other line, sissors or a knife, the line hook on some knives works well.
4) cutting steel leader (this is used for commercial fishing for sharks and other toothy fish), shears (emt shears are fine). a knife is a poor second place. the line hook is of little use.
5) Kevlar line. I have limited experience with kevlar line, i have used kevlar yarn (cloth) and webbing (climing loops). Use a knife with a sawing action. Sissors may work for a bit.
6) spectra line. I have not actually dealt with specta line, my expereience is with spectra yarn (as in cloth) and flat webbing. Use a knife with a sawing action. Sissors are useless. common household sissors will not cut webbing ever. heavy special sisors with seramic cutting edges work though.
7) Steel cable, chain etc. Use a cutting tourch, hydralic , pnumatic or explosive cutters. Sissors and knives are useless...