Saw this in a blog post: 「悲しきかな読書への愛を育むほどに、夢は現実から遠ざかる」 It seems like 「悲しきかな」is used as a na-adjective (形容動詞). Is this correct? I've never seen this form of adjective before, what would its conjugation be?
No, it is not an independent adjective, but can be divided as 悲しき + かな, where 悲しき is a classical 連体形 (pre-noun form) and かな is a particle
Preceded by nouns or pre-noun form, indicates being impressed/exclamation. Translated as だなあ.
So a modern version would be 悲しいなあ, meaning oh, how sad...