Burke; first of all, neither 1095, nor 52100 are tool steels. Check it out for yourself. Go here:
Look up 1095 under carbon steels, and 52100 under alloy steels.
So, what is the freaking difference you dilettante doctor?? Well, actually, Burke, it is not a cut and dried distinction. To get a feel of what constitutes a tool steel, I suggest the superb FAQ's by Joe Talmadge, located along with a lot of other great information in the knowledge base section on BFC's home page.
Another good place to learn about different types of steels, and what a tool steel is, is the Crucible Particle Methodology website:
Click on 'Heat Treating and Fabrication of Tool Steels.' Then, click on 'Tool Steels,' this will give you loads of information on the different types of tool steel, both CPM and traditional ingot type, which are available.
In addition, the 'Tool Steel' site has a great topic contained within it; 'Selecting High Performance Tool Steel.' I find myself going back and reading these often. In fact, in composing this post, I found a new steel, T15, on the CPM site. It has some very interesting components and characteristics.
While the information is presented in the above references much better than I can, let me just say that tool steels are designed to work other steels; therefore, desired qualities are hardness, wear resistance, and toughness. The maintaining of strength while hot is also useful in tooling, but is of no importance in knives.
Just remember that there is usually a catch. In the case of tool steels, it is lack of corrosion resistance.
I have heard a lot of good things about 3V, but have no first hand experience.
Hope this helps, Walt