I have a feeling this thread will need to be a sticky
I love a good pair of end nippers but i have always used vintage ones, I like the compound kind since it makes the job a bit easier.
A set of flush cutters are nice to have around but my last pair broke and i hvent gotten around to orders a new pair.
Backspring compression device, priceless.
hammers are a must, I like a couple, one rough hammer for beating on stuff, and a polished face hammer or two for pin peening and operations where i dont want to mar any surfaces.
pin punches, you will break some, especially the thinner ones I finally made my own with replaceable tips
A Vise, a smaller one will do but a mid size one or a couple different ones is nice to have around
An anvil or stiddy of some sort is a must. I like a stiddy but if you don't plan on trying to peen scale pins on an assembled knife they are pretty much an unnecessary expense, you can get by with a couple chunks of steel large enough they won't bounce around when you hammer on it. I used a machinist vise for years as a vise, anvil and stiddy and it worked fine. A purpose made stiddy just simplifies things a bit.
Files, a hobbyist can get by with a few files, I suggest a 6" and/ or 8" mill file, a 6" slim taper triangle file, a chainsaw file or two and maybe a half round. I have dozens of files I use but I do a lot of filework and other specialty stuff that require them.
A scratch awl is indispensable for marking things.
Rotary tool, dremels work fine, used them for years, eventually upgraded to a foredom with foot control, excellent investment.
Then you have your bigger power tools that make things go much quicker, a belt sander, disk sander, drill press, band saw and buffer.
a Welder for specialized jobs