Space bar works for me to transfer items into the Clan Armory, but only from the Crafting Table window. If you do it via the Clan NPC screen, it does not work, despite the tooltip saying it should.
Hopefully putting non-used items directly back into your inventory is something Shadow is going to implement, because it's definitely needlessly messy right now. Or, alternately when you're in the Clan NPC screen or Crafting table, there could be an icon denoting which items would be equipped by a clan member, so there isn't any guesswork or need to filter them all through the Clan Armory. (I like this a lot better, but I don't know if it's feasible.)
I've also suggested having additional hotbar-like buttons show up only when you're in your town, which would have buttons for the Crafting Table, Bulletin Board, and Town Defenses (and maybe the two stashes as well). I feel having these as buttons together would make it much less confusing for new players, as well as much more convenient so you didn't have to do quite as much running back and forth between the objects (which admittedly aren't THAT far apart, but why not streamline it?).