In the show, though, Witches really never need a weapon to channel their magic with. They always just chant and it happens. And, even if you did want to give your witch a staff or wand, you could just put it in the bio. Or, if you wanted to make a living staff or wand, then you could just make them a normal Weapon, Dark Weapon, or Demon Blade with the effect of channeling magic.
As for familiars, we already just let people have free reign with them as long as they're not completely unreasonable, such as cats the size of skyscrapers or something. They're just counted as NPCs and players are allowed to just do whatever for the most part.