I think the đ in Ađelstan is (or was!) pronounced as the TH sound of "the." AĐELSTAN or ATHELSTAN. Would be fun to bring back the eth Đ and the thorn Þ, am I right? Đis could be đe future, just þink!
In Wales the name Æðelstan of the 900's had evolved into Elystan by the 1100's. æðel "noble" and stan "stone" further morphed in the latter half of the millennium to ELYS, ELIS, and ELLIS.
The evolution of the name ÆÐELSTAN over the millennia in Wales has IN SOME INSTANCES morphed as follows: ÆÐELSTAN --> ELYSTAN A Political History of Abbey Cwmhir, 1176 to 1282: and the Families of Elystan Glodrydd, Mortimer and the Princes... by Paul Martin Remfry and David H. Williams (Feb 1, 2003) ELYSTAN --> ELYS, ELIS, ELLIS.