You don't need certs for items. I don't know why you think you do.
You do not need a cert for a magic item awarded by an AL-authorized adventure, that's true. If it's true that everyone who played the Season 4 epic got a special award, then I'd expect to find that on the Organizers site or from some other official source, not hear it for the first time in a thread on EN World.
Our RC went to Winter Fantasy and ran some modules there; when he returned, he said nothing about special awards handed out as part of the Epic module. I'm sure I can ask him the next time I see him, but that would have been a good time to spread the word about these non-standard awards. Otherwise, as a DM, I have no real reason to take a hand-written cert at face value.