Of yore and Once

Once and of yore are semantically related in old topic. In some cases you can use "Once" instead the phrase "Of yore" as an adjective or an adverb, when it comes to topics like previous in time or order, previously in time or order. obsolete substitute

Once adverb - At an earlier or previous time.

Of yore and once are semantically related in in days of yore topic. You can use "Of yore" instead the word "Once" as an adverb or an adjective. literary substitute