Worked as Weber State University Police ten years ago. Here's my input:
If you are going to wear the costume on campus, reach out to the university police (many universities employ state police officers with full- time arrest authority, not just security guards) and talk to them before you go. You will speak to their dispatch, whatever that looks like, instead of an officer, and that's fine. Tell them your plan and ask too have a patrol officer call you back.
When that happens, tell them "hey man, I'm *insert name here* and I have a halo costume I would like to wear on campus." They will say "Dude, that's sick!" Unless they're dead inside, in which case they will say "oh. Okay, so?" And then tell them, "originally, this costume had a fake weapon, but I do not intend to bring it on campus because I don't want to cause problems."
The guy will say something like "eh, that's fair." And ask generally where you will be and what times. They ask this because when, not if, somebody has a problem with such a 'violent scary thing' on campus the officers can say "yep, *X place* at *X time*, it must be *insert name here.*
It is very likely one or more of them will show up to look at you. They do this for several reasons: First, it's awesome and not a lot of people have as cool a costume as Halo running around. They might ask to take a picture with you. (Local police did that to me in my Reach suit once.)
another reason may be because somebody DID call you in as a suspicious person or whatever, and since they are obligated to investigate such complaints, they have to come make sure you're not blowing up the quad or something like that.
More than likely, as soon as they know who you are and what you're planning on doing, you will not have problems at all.
You can speak to the officers specifically about their policies on your fake weapons, but like
Cadet and
N8TEBB have said, it's best to leave them behind.
Hope this helps.
