Board Thread:General Discussion/@comment-7779702-20130404000656/@comment-5398287-20130404162131

Well, it would be interesting if Kubo gave Isshin a Kido-type Zanpakuto, as that would likely influence Getsuga Tensho and Saigo no Getsuga Tensho if it were a fire-type. However, I'm unsure if this was planned in advance, as during the Arrancar arc, when Isshin finally releases his Zanpakuto (admittedly for all of 3 seconds), there isn't any fire, just a regular Getsuga Tensho. I'm not saying Kubo wouldn't retcon that, but I'm not sure how he would explain it.

However, I feel that I should address the release command. While Burn is an intransitive verb most often relating to fire, we cannot say by that alone that this is a fire-type Zanpakuto. I say this because 1. other fire-type Zanpakuto have release commands not relating to fire (Snap, Tobiume; Crush Down, Tengumaru; Sever, Raika), and 2. more than a few Zanpakuto have release commands not relating to the special ability at all (Flower Wind Rage and Flower God Roar, Heavenly Wind Rage and Heavenly Demon Sneer, Katen Kyokotsu; Awaken, Benihime; Rip, Ashigozi Jizo).

However, now that I think about it, if anything, Burn may be referring to the appearance. Take Hisagi Shuhei's Kazeshini, for instance. Its release command is the intransitive verb Reap, yet it doesn't kill in one hit or command the souls of the dead like some God of War III Hades rip-off. Instead, the command relates more to the appearance of the Shikai, which is two scythe-like blades attached to each other by a chain. So by and large, this command may extend to appearance only. Just something to keep in mind, I suppose.