My English great-aunt Isabella, universally known as Bella, used to put her name on envelopes as part of her return address, and there it was always Isa. (With a full stop: Mrs. Isa. Lastname.) Other relatives confirmed that it was pronounced IEza, though Isabella had the usual pronunciation.
Would it even be correct to say that the name of a rune is used as a given name in modern English? They might well share the same spelling, as do polish (for furniture) and Polish (from Poland), but so what? Everything else is different.