From my reading of Dweomerkeeper and domain description in PHB/SRD, Biggus is correct.

Without abilities you haven't indicated, you could select Limited Wish as a 7th level divine spell for Mantle of Spells. Even if Anyspell could work on 7th level spells, I don't see how you could choose it as arcane. As functionally a cleric you'd want it divine anyways.

The logic of the wording is supported by clerics ability to use wand/staff of a spell that is only on their domain list. You can only prepare 1 7th level domain slot, but you can convert spells to 7th level+ spells you *know* as many times as you have 7+ level slots.