Attainment, n.
1. The act of attaining; the act of arriving at or reaching; hence, the act of obtaining by efforts. The attainment of every desired object. Sir W. Jones.
2. That which is attained to, or obtained by exertion; acquirement; acquisition; (pl.), mental acquirements; knowledge; as, literary and scientific attainments.
Shades of meaning
Fernald has no entry of its own for attainment; he lists it under progress, wisdom.
Where he writes about it:
Attainment, development, and proficiency are more absolute than the other words of the group, denoting some point of advantage or of comparative perfection reached by forward or onward movement; we speak of attainments in virtue or scholarship, proficiency in music or languages, the development of new powers or organs; proficiency includes the idea of skill. — from progress