Knives and swords are arms, yes. This was most recently seen in states that tried to ban switchblades outright. Switchblades are pretty poor fighting knives, but have the same public reaction fueled by media as pitbulls.
I talked with a lobbyist responsible for the switchblade deregulation in my state. After her research it came to "What makes a weapon will always be up to the judge, but the easy test is can you swing it?". Which is fair I think. That said... I also trained with my state's swat unit for a class and they talked about their justification for getting their gun out according to dept policy being "Any time a weapon is involved", which can mean gun, knife, sword, folding chair, sharp pencil or really big box of hot dogs depending on intent.
You're right about the tank. So long as you have the right markers, mirrors, vision, licensing, etc. You're good to go. Although you won't enjoy it as a daily driver after the initial buzz wears off.
Since you seem to know a lot about "arms," is a sword an "arm?"
> functionally different than:
I believe you can take your tank off your property, assuming you went to the DMV and got license plates and a VIN number for it.