When I studied Anglo-Saxon, it would have been DAY-or-wee-na, with a lighter stress on the -wee-.
Modern names like
Selwyn show that -wine became -win as the language evolved.
There is a remarkable poem entitled (or written by - nobody knows!) Deor in which the speaker, alone and friendless, cheers himself up by reflecting on sad stories of disasters that have befallen other people, with the refrain "That overpassing, this also may". A stoical person!