I carry at two as a minimum. I have a Victorinox Swiss Army Super Tinker Pocket Knife and a Kershaw Shallot 1840 that I always carry. There are times that I may add some or all of the following: Kershaw Leek 1660, a Victorinox Swiss Army Classic SD, a Gerber Gator®, a Leatherman Super Tool, and a Leatherman Squirt E4.
It all depends on where I am going and what I am planning on doing. If I am going somewhere that I cannot carry my firearm, but I can carry the a knife, then I'll load up on the knives, especially the Kershaws and the Gerber Gator. I think of it like I do conceal carry, if it is in your pocket (if the knife is legally concealable), then what they don't know won't hurt them. The Gator I carry on my belt in the pouch that came with it, the others are either in my pocket or clipped to the side of a pocket.
The Super Tool and the Squirt E4 are tools and cannot be (under normal circumstances) be used as a defensive weapon.
The biggest thing is can you justify the reasons for needed the knives that you carry. The one of the two main knives that I carry was frowned upon by the district manager at my work. He said that the Kershaw Shallot was not a knife that I needed to carry at work and it could only be used as a weapon. I showed how I could use it at work as a tool and I am allowed to carry it.
Kershaw Shallot 1840, Kel-Tec P-3at, Kel-Tec PF-9, Glock 17, Glock 19, Glock 26, Kel-Tec SUB-2000 9mm (Glock 17 mag compatible), Maverick Arms 88 Security 8-shot 12 gauge.