Uhm, seeing how we've got one on the flight deck already ( making sure to procure the exact same type as that one, so that it's a like-for-like situation ), next time you head off for work why not pop a fire axe in your flight bag ?
I can see it now.......
Security nerd - "What the hell is this ?!"
Pilot - "It's my personal fire axe. It's precisely the same as the one we already have on the flightdeck."
Security nerd - "But you can't take this through security, it's not allowed."
Pilot - "But as I say, there's already one on the flight deck which is exactly the same as this - this is simply a backup to that one - in that it's always handy to have two of everything, e.g. should one break, etc ... a bit like why we have two or more engines."
Security nerd - "But it's not allowed !"
Pilot - "But there's already one there that's the exact same as this - so why can't I have my own personal one as well ?"
Security nerd - "You're taking the P out of us, aren't you ?!"
Pilot - "I'm saying nothing."
etc...........
Oh yes, there's hours of esoteric fun to be had with this ( ok, probably not ).