How long IS this sword?  How big is that _jacket_??

Observe this simple handkerchief; observe this battleship...

The problem here is that while we can expect that sort of thing from Ranma
(his mastery of magic has plenty of foreshadowing), I can't recall a single
instance in the previous chapters where he taught Akane the trans
dimensional pocket technique.  Previous chapters have established a long
and detailed pattern of rational explanations for the various chi
techniques in this story, so having someone able to use one "just because"
is a disappointment.

Actually, it was mentioned in 4C, to whit:

---
   A small patrol was closer than the other strays and had set a 'trap'.
Unfortunately for them no one had thought to tell them about Sayuri and
her knives. Thus, when a thorny bush tried to ensnare Sayuri, she had a
knife out and hacking branches inside half a second. Blessing Ranma's
instruction in the simple trick, Akane drew a tai-chi sword from
jacket-space and cut the bush off at the roots. The two girls continued
running ... which is why they weren't where the demons had anticipated
when they sprang their ambush.
---

Morpheus the Shaper
http://milamber.home.mindspring.com