A word of wisdom: Do NOT by any means call it Ozerbius, especially when casting a spell. Alternate dimensions and realities can clash causing terrible things to result (such as munchkins appearing in the wrong places).
I pronounce it (ih-serbius), for several different reasons..
Y -> I is a linguistics trend in many languages, dead and alive
cf. english (where Y and I have been mostly merged), welsh (still using Y, cf. dafydd for david) and in many other languages (notably the transcription of the play 'Tristan u Yseult' as 'Tristan and Isolde')
The name Yttrium, an element, is pronounced as "Ittrium", not "Yuhttrium".
Also, Y tends to be pronounced as a vowel (I) when in front of a consonant, and as "Yuh" (a consonantal sound) when in front of a vowel.
Yesterday, Yeast, Yes, etc... as a consonant
Yserbius, Ybarra, Yttrium, Yseult, etc... as a vowel, short I or long E.
obtw. Ybarra is pronounced "e-(B)AR'-ra" with a long E and a rolled r, and a b somewhere between B and V (the spanish "be grande".)
That's how I said it, too. And a co-worker of mine knows Joe Ybarra -- it's EE-bah-ruh. (Edited because I actually heard his voicemail today on speakerphone, it's EE-bah-ruh not Yuh-bah-ruh as I thought).
pronounce it the same way. Being from California where Spanish is blending in with English it just makes sense to me to pronounce it that way, but it is fun and interesting to see other's pronounciations.