People who uses double weapon in "real life" don't really favor one end of the weapon over the other. Since that weapon is normally twirling around, it is understandable that both end keep the off-hand property.
Just for the record, I built a tempest fighter that wield a whip and a handaxe. Both weapon have off-hand property and the whip is the only weapon with both off-hand and reach. I suspect damage will be pitifully low, but that fighter can easily mark two targets per round and with reach for one of them.
Hmmm, Indiana Jones with a whip and a hand crossbow, with the feat that make hand crossbow an off-hand weapon. Why do I keep having those crazy ideas that keep my players groaning. Now I'll have to make a recurring NPC solo adventurer with this idea
