V2 vs Vy
From the standpoint of the pilot, one can consider V2 as the one-engine-inoperative (OEI), best-angle-of-climb speed. In reality, V2 is actually not optimal, that is, it is usually somewhat below the OEI best-angle-of-climb speed. There are, also, certification issues involved in the computation of V2.
Airbus has a series called "Getting to Grips". One of their articles is entitled "Getting to Grips with Performance". You can download this and read for yourself how the various V speeds are derived. It's a rather lengthy paper...over 200 pages...but, it explains in simple terms and in detail all about performance.
PantLoad