You mean so only the admin/host can spawn them?
simplest way to do this is bankick people if you see them with an admin only itemotherwise, there should be an RTB pref and a big item list and you could set it to "All, Admin, or Super Admin"
Why do you need host/admin only items?
But then people wouldn't like me and it's brutal and not that well executed.
What I'd do is make a box somewhere noone can get, then use Admin Orb / Comet (etc.) to get into it, and put the weapon / item in there, or wait for someone to make your idea.