My "suit" knife is a A.G. Russell 3.0 Titanium lockblade. Weighs 0.9 ounces, very thin, 2 1/4" VG-10 blade for 34.95.
^^^This, or a Spyderco Kopa in CF or giraffe bone is what I carry for suit duty. The really nice thing about these knives is if you use them as money clips, nobody even has to know you are carrying.
Sadly suit or slacks pockets are crap for carrying most anything in one's pocket , in my experience. You would be better off with something small and very light. This is the best suggestion so far , I think. I have one and it is small and slim , very light but will cut what you need to cut. One the few times that I am forced to wear slacks or suit pants ( which I detest with a burning passion.. ) I choose this knife , I cannot stand having lumps in my pockets when I have to wear those terrible , terrible excuse for pants. edit - mine is actually the 2.5 lockback version. Tostig
William Henry Monarch B5 CFD: If you are in a state that allows automatics, consider a Pro-Tech Brend 3 Tuxedo model...
TBH, anything without plain plastic/metal/G10 handles would look fine with a suit and tie, like micarta, semi-precious material inlay, polished/jigged bone, stag, etc., or anything with a Damascus steel blade, because Damascus does look quite class.
If in formal wear I would just recommend something slim/slender/thin as you do not want bulging pockets.
Al Mar Eagle. Black polished linen micarta, with satin blade and black/red clip. Classy, and pretty much the lightest folder of its size.
Thank you for the responses guys! Quite some pickings? I love the Moki and the William Henry Monarch posted above. And I think I am beginning to like some of the Case knives a lot more now! Thank you!
As 6thtexas stated above, the A.G. Russell Titanium lockback (or is it lockblade?) knives are great for in-pocket carry - small, well built, very sharp, and they come with a nice leather sheath that helps protect the pocket from the knife and the knife from stuff that my be in your pocket. I like them a lot, carry one often and give them as gifts occasionally. If, when you say formal, you want a fancy knife for a fancy suit that could also be a conversation piece in a fancy suit crowd, and you have the discretionary funds, then William Henry has a lot to offer. And I mean no disrespect when I say "fancy". The William Henry knives could be described that way but I see them more as incredibly artistic, imaginative, precision built, very useable knives - including Deferg10's in the above post. Many also come with a leather carry sheath. Though I've not had to wear a suit for a long time, I have treated myself (my wife often suggests I buy my own birthday present) to a couple over the years. You might also like their E6 model. Depending on the direction you want to go, there are a number of good custom makers on Blade Forums also. Mike
I usually go with this little Ohta Teardrop slipjoint. It's as light as pocket lint, only 2-5/8" closed so it won't spook the herd and, IMO, pretty classy lookin'.
I like a Victorinox Swiss Army Knife in Alox. Usually a silver cadet. Slim, small, non-threatening. Cuts stuff if I need it.
For modern folders, William Henry makes some very nice gents folders, and the Mnandi is a good suggestion, too. If those are out of your price range, try a BM Shoki in CF/M390 A Spyderco Bob T Slipit A Spyderco UKPK (sorry, no pic of my CF, but it looks just like the Caly 3 below), or one of these - Caly 3, Leafstorm, small Sebenza, Buck Waimea And if you like traditional slipjoints, either of these from Great Eastern are good, and they also have some smaller patterns available, such as the Conductor I should also add that the Moki lockbacks are top quality, too.