I'm not a metallurgist, but here is some info I gleanded from a few places:
1095 is simple stuff, just iron with about 0.95% carbon (0.9 - 1.03%) to make it "steel", and 0.3-0.5% manganese to improve hardenability, strength, and wear resistance a touch.
To that mixture, you add the following to get 0170-6, which is considered a simple "chromium carbon steel":
0.45% chrome
0.2% vanadium.
Chrome in low concentrations helps with toughness. (Of course at high concentrations, say above 10-12% I'm guessing, chrome impedes toughness, and significantly up at the levels seen in 440*).
Vanadium at low concentrations helps refine grain structure (makes it finer, smaller). It may combine with carbon to form a small amount of Vanadium Carbides at these levels, very slightly improving the abrasion resistance, but not appreciably. It's a grain refiner at these levels.
(If someone knows this subject better, please dive in and straighten me out here)
A2 has a somewhat more complicated formula and is getting into a more complex alloy. It is an air hardening tool steel (use to make machine tools and cutters for cutting other steels, and for wood, e.g. hand planers), and goes like this:
0.9 - 1.05% carbon
4.75-5.5% chrome
1.0% manganese
0.9-1.4% molybdenum
0.3% nickel
0.5% silicon
0.15 - 0.5% vanadium
Manganese is a deoxidizer in the smelting process. It somehow scavenges oxygen and apparently causes it to leave the melt somehow, I guess by bubbling out, but I haven't read anything on that mechanism.
Molybdenum helps to prevent deep corrosion pitting, and improves hardness (molyb carbides).
Nickel improves toughness and flexibility.
Silicon improves tensile strength and depth of hardness, and I think aids impact resistance (a toughness thing).
Now, I don't have experience with 0170-6 and A2 side-by-side in similar blades (or even better, in identical blades). A2 has the potential to make a somewhat better balanced overall blade, being plenty tough for most things (probably less tough than 0170-6) but adding some abrasion resistance to improve slicing type edge holding versus 0170-6. A2 is best if taken up to around Rc60-61 (where it appears to have a relative toughness peak).
But 0170-6 is an improvement over 1095 in my book, [edited to add that] particularly where a stock removal process is involved, as I don't recall seeing a hand-forger who used 0170-6 (which may have more to do w/ availability than with forge-ability).
The key for either is to receive a high quality, optimized heat treat. My Camillus Fisk Magnum and Patrol Machete are both good designs (important) and the steel seems to perform very well, subjectively. So my knives seem to have gotten a good heat treat.
Hope that helps.