It's a master key, aka. skeleton key.
They're illegal to have without proper authorization, from what I've heard. They're for repo men, locksmiths and such.
A person can get in trouble for having one if they're not licensed for it.
Hondas are much more likely to be stolen by use of more common tools and bare hands. Shaved or filed keys are more likely to see than master keys. Even normal keys with wear can often work on other cars of the same make since the lock cylinder are subject to wear over time.
The truth is, these old Hondas are incredibly easy to break into and there is no reason anyone would need to spend money, effort or time getting a master key to break into one.