Why was derringers nerfed?

[Paineframe]

Wouldn't two 125-brute shots put you into extremely deep crit with a fairly high chance of killing the target near-instantly?

Anyhow, as I read it, the reason Marq nerfed the derringer was that, before his change, derringers did half damage against unarmored people and triple damage (plus negating the armor's protective effects) against people wearing weak armor.