expression, noun
able person; person of talent
A somewhat literary set phrase meaning a capable or talented individual. Not an everyday colloquial term; more likely to appear in formal writing or elevated speech.
彼はまさに有為の材として期待されている。
He is expected to be a truly capable person.
人材 is a general term for 'human resources' or 'talented people', whereas 有為の材 is a more elevated, individual-focused phrase.
有為 (ゆうい) means 'capable' or 'promising', and 材 (ざい) here means 'material' or 'talent'. The phrase literally means 'material of promise', i.e., a person with the qualities to achieve great things. The exact historical derivation is uncertain, but it follows classical Chinese-influenced phrasing.