So she's been disguised as a cane this whole time! (Adding that to the list of things zanpakuto can do.) Although, wait a sec--I distinctly remember Urahara using that thing a couple times to knock Ichigo into his soul reaper form.

Like in chapter 29, when Rukia was too busy being dogpiled by security to punch Ichigo's soul out of his body:

And then again in chapter 53, when Rukia was too busy being confronted by Renji and Byakuya to punch Ichigo's soul out of his body:

I can't help noticing that both of these times, the bottom of the cane has that same flaming skull we see on Rukia's soul-ejecting glove. And I've been squinting real hard at any times the cane shows up this chapter, but I can't tell for the life of me if it still has the same marking now. (Mostly because it's always turned away from view so I can't actually SEE the bottom.) So maybe the marking is something that can be put on or removed when he needs to eject a soul instead of stabbing them? Kind of like putting a pool noodle on a goat's horns to keep them from stabbing things. (Now I'm making myself laugh at the stupid mental image of zanpakuto with pool noodles stuck on the tips.)