I have no doubt that some if not all of these will be illegal in many places, so I’m not advocating anyone actually purchase these, but I thought the concepts were good for a laugh.
You have such things as the knuckle duster case, pepper spray case and stun gun case.
Weaponizing a phone sounds very manly. Girly girls might need something a little more dainty.
Those are all cyoot and all but when something more srs in the way of weaponry, say for zombie attacks, is called for:
I’m not really sure what to say about that. Would definitely want to see a lithium ion battery for it though. 
Been into duct tape recently. I’ve made a tri-fold wallet and a coin purse for myself. For my wife, I want to make her a hand-held billfold. It will have a sturdy wrist lanyard to make it hard to snatch. One end will have an internal coin purse which, when full, will turn the thing into a flat sap. And if things get edgy, Opening the flap will reveal loops holding a short knife and a tactical pen/dagger.
Not for boarding planes, just a stroll around the market place.
Uh, let’s remember to maintain some gender equality here, people: Will those things be illegal too? 
I was thinking about a lighted stun cane myself. Since I was a kid I’ve always wanted a cane sword but I’m sure I’d get locked up if I ever got caught with that.
I don’t have a stun cane, but I DO have one with a multi LED light and a compass on it. Unfortunately, you can’t use the light on the compass, you can only use the compass if you have another source of light. This cane is pretty handy when you’re trying to find a keyhole in the dark, though.
You should get the stun cane and one of these for the other arm. If they don’t shit their pants when they see the electric current arcing across the end of your cane, you can just take their heads off with one clean swipe. 
If I’m gonna carry a sword at all, it’s gonna be a Buster Sword or a Fusion Sword.
Olivier’s retractable forearm blade from Marathon Man is the only way to go. Is it safe? Probably not