About 未知なる

I've come across 未知なる quite a few times, most notably in song lyrics, but also on webpages. The general translation seems to be identical to what it would be if it were 未知な. So, is this for stylistic purposes, something peculiar to 未知, an abbreviation of 未知になる, or is it another usage/method of conjugation of なる? Thanks a lot.

Also, most of the occurences I've come across seem to be somewhat philosophical? in nature:
未知なる深海
未知なる世界
未知なる展開
未知なる蹄跡
未知なる宇宙etc.

That なる is 連体形(adnominal/adverbial form) of a classical auxiliary verb なり, which is equivalent to だ in modern Japanese. Thus, なる can be considered as the classical form of な, as you found out. Because of that, 未知なる has a dignified/formal nuance.
As for your examples, 未知の would be more appropriate to be replaced with 未知なる than 未知な.

Toritoribe said:

That なる is 連体形(adnominal/adverbial form) of a classical auxiliary verb なり, which is equivalent to だ in modern Japanese. Thus, なる can be considered as the classical form of な, as you found out. Because of that, 未知なる has a dignified/formal nuance.
As for your examples, 未知の would be more appropriate to be replaced with 未知なる than 未知な.

Click to expand...

Oh, I understand now... but that brings up another question: what's the difference between な and の when both can be used?