I believe edge bevel is the degree your edge is at. So say you have a 0 degree bevel, your base and side edges are at 90 degrees. If you have a 2 degree bevel they are at 88 degrees. If you detune the edge, it dulls them, so the angles is farther from 90 degrees, so yeah you are changing the bevel.
Thats just what I think I know. If I am wrong, some else correct me