For cutting line (I use PowerPro), I've tried all kinds of gizmos from nail clippers, Leatherman tools, Chinese copies of Leatherman tools, to scissors, pliers, jackknives. I settled on the Kershaw Double Cross jackknife, and I love it. About all I can't do with it is take it on an airplane! Here's their ad:
The Double Cross: New, with the "Double Duty", these double-bladed knives feature one-handed opening and traditional look. Try one. Try two. These knives feel good to carry.
They're on
www.kershawknives.com.
I got mine about five years ago at Narragansett Video shop in Wakefield. It's best features are that it'll sharpen like a razor and, handiest of all, it's openable and closeable with only one hand, has two blades, is small and light, and it locks open. For fishing, jackknives are a problem when you have to use two hands to open and close them. This one works great with just one hand (with a little practice.)
I don't get a commission on these things, I just like mine and carry it everywhere.