As for the name pronunciation, don't be a weeaboo. Aegis is an English word, I believe, often used in reference to certain military technology and it is pronounced Aye-Gis. Maybe this is what the creators intended. I mean, it's not like the Japanese don't have a history of mispronouncing English names all the time: (See: Gurren Lagaan: Simon)
surasshu said: It's a Greek name technically, but you're right about the pronunciation.
Well, let's be honest. (Modern) English is a relatively new language. ALL of our words are taken from something else.
But yeah, point is, just because the Japanese pronounce it as such doesn't make it the actual name. In Death Note, it's Light, not Raito. Aegis isn't a Japanese name, but the original cast is Japanese, so they pronounce it like that. But that doesn't mean that's her actual name, it's merely how the Japanese tongue works.
It actually should be spelled Aigis, since it's Greek αἰγίς (aigis), Latin is Aegis. The originally Greek work stems from αἴξ (aix), meaning "goat", "goat fur". It usually refers to Zeus' Shield, it was also used by Athena at Troy. Also, the Japanese Voice Actors say "Aigis", too, and use it as a kind of pun when Junpei calls Aigis "Ai-chan" (Ai being a japanese women's first name and meaning "love").