Buck
I'll be the Buck Knives guy this evening and let someone else offer Kershaw, Gerber, and Spyderco.
Buck does a number of robust folders that have "tough" and "sharp" in their descriptions. All made here in Idaho, and backed by their "forever" warranty..
The Buck Sirus #297 and #298 are heavy and solid, with nice, sharp edges. The #297 is their standard 420HC steel. No complaints. The #298 is S30V steel with Paul Bos heat treat. Either of these is excellent. Both are assisted openers. The #297 is in the $60 range, while the #298 is in the $90 range, depending on where you shop.
Buck does a couple of lighter models, the Rush and Tempest, also assisted. The Tempest is the same size as the Sirus, the Rush is smaller.
I have both the #297 and #298, but I don't regularly carry them. They're a bit heavy for my "slacks and shirt" environment. When I do carry them, I use a horizontal belt pouch.
Buck has recently released a new line of folders with which I'm very pleased: the Buck Vantage series. The Vantage Select (#345) is their standard 420HC steel and has black FRN (fiberglass reinforced nylon) handles with steel liners. It is a one-handed knife, but not assisted. The Vantage Avid (#346) has 13C26 Sandvik steel with Bos heat treat and charcoal "Dymondwood" synthetic handles. The Vantage Pro (#347) has S30V steel with Bos heat treat and black G10 handles.
Pricing is roughly: Vantage Select $35, Vantage Avid $50, Vantage Pro $75 -- again, depending on where you shop.
The Vantage Select is also available in a "small" version (2 5/8" blade) for a few bucks less.
For what it's worth, I carry a Vantage Avid (the Sandvik steel) as part of my EDC loadout. I'm quite pleased with it. No, I have not tried to pry open a car door with it yet, and somehow I'm thinking that won't happen. It does a real number on cardboard boxes, though. And I use it in the kitchen for veggies and stuff. Not too bad.
The Vantage series is quite flat and they carry well in pocket.
I should clarify the "not assisted" thing. They can be opened with the thumb, using the thumb hole in the blade, or they can be flipped open using the flipper tab and a wrist flick. Takes about a minute, maybe less, to master that. I can get mine open nearly as fast as my assisted ones (faster, actually, if I've engaged the lock on the AO).