I don't remember them saying anything about why it was a gun in the games. Maybe in the manga or anime they mentioned it.
Based on what everyone has said, here's how I intend to run this roleplay:
Evokers are a definite no. Based on what has been said I think we should have a focus of some kind, but I think I'll leave it up to each character what they want it to be. Since a persona is another side of a person, I think the focus should be relative to who that person is or the persona they are summoning.
I like what Who mentioned with the appearance thing, however that might be a bit awkward with certain persona's and their users. Thus I've decide that in the gameworld, the characters will have the option to take on traits of their persona appearance wise, but will otherwise be themselves. I'll admit, it irks me that the students in the video games always run around in their school uniforms when exploring. Aren't they worried their uniforms will be ruined by combat? Plus, their uniforms provide little to no protection against the shadows.
Speaking of combat, we're going to handle it much like the games. I've GM'ed several games before, and what I've discovered is that excessive combat, and/or excessive dice rolling takes over the rp. To alleviate that, I'm going to reduce the number of battles a bit. They'll still be plenty of combat, no worries, but most battles will be fighting normal everyday shadows. For fights like that, I'll leave it up to the players to role-play it. Most of those battles shouldn't be more than two or three posts per player at the most. However, significant story related battles, such as boss fights, those will be handled by a simple dice system. We'll worry about crossing that bridge when we get there though.
Other than that, I plan on setting up the in character thread either tomorrow or Monday. I've got some stuff I want to look up first before we begin. As always, if you have questions or concerns, feel free to bring them up or contact me.