well, i saw Ascevedo and Azevedo, and i took a look in my Spanish for Dummies book (lol, it isn't called like that) at the pronunciation and i saw that the 'c' and the 'z' for an 'e' are the same pronounced (like 'th' in thing). so that's how Ascelin could become Aszelin and then Azelin.
so in Spanish, it's AHS-ze-lin (with the 'z' pronounced like 'th' in thing)
in French, it's AHS-se-len (the 'e' pronounced long and the 'n' hardly pronounced or not pronounced like AS-se-lè)
in English, it's AS-se-lynn (like that, thus AS like in ASpen
hope i helped here