hopefully we get to see it soon! i think it will be pretty immense
Well, his shikai seems to be related to energy blasts or some sort of Kidou, so I think his bankai would be an enhanced version of that; and about how it looks, I'm seeing it as nothing big and flashy, but a subtle and elegant appearence.
Well it was hinted that his Bankai isn't suitable for training so it may be that it's because his Bankai is defensive or it's a supportive Bankai which offers no offensive boost.
Benihime, Crimson Princess, by the name it may be possible to decipher the ability of the bankai or even why he doesn't use it. There may be some odd manifestation of the bankai that causes a female avatar to appear and get all posessive of Urahara and most likely start a fight with Yoruichi to "step away from her man".
The word Princess could also suggest some sort of Dominance when used such as the Bankai manipulates the target and draws the blood out of them like a Vampire which is why his blade is known as the Crimson Princess. A loli vampire with a bloodlust which uses said bankai to draw blood from the target to empower his other abilities.
Maybe that's where the two kids came from, they were unfortunate victims to Urahara's untrained bankai. Upon first using it the bankai manifested and targeted both Ururu and Jinta turning them into the superpowered children they are now.
Though maybe the mystery will be solved soon, if his Bankai/spirit is as restless as I think it is it's quite possible that he'll purposely have it stolen just so that he can have her torment the person attempting to take her away from the love of her life.
I think his command would be something like "arise" Benihime of hell (<don't know translation) and maybe it works as a manipulation Bankai (like TheWanderer said) but it controls reiatsu
I did some Zanpakuto brainstorms a while ago, either inventing new zan's or completing existing ones, like Benihime. Just for the lulz I'm gonna share one I cooked up though I'm quite sure the real one will be very different.
Release command: Awaken now, Benihime!
Description:Straight blade, guard is folded around it. Hilt has a slight
curve at the end. Has several blood-based energy attacks, such as:
-Scream Benihime, a shot of crimson energy in the shape of an arc
-Blood Mist Shield
-Razor Benihime, a shot of energy capable of piercing and cutting tough
surfaces, can change directions at the users will.
-Spurning Benihime, cancel out an oponents reiatsu based attacks by drawing
a circle after observing their attack.
-Binding Benihime, a bloody energy net.
-Fireplay Benihime, explode previous net.
Name: Majin Benihime
Description: blood from the user seeps from his body and shapes into a mist
surrounding him. This mist coalesces in the form of a spectral, demonic lady,
surrounding and protecting the user, like susano'o. Starts out as a vampiric
skeleton with horns. The user must sacrifice a lot of blood to activate this
bankai. The user must already be significantly wounded to provide
ample amounts of blood. The spectral form greatly protects the user and can
be controlled. It is capable of similair energy attacks usng it's claws. The
magnitude of these moves is far greater than Shikai. Each succesfull hit
results in a wound that bleeds profusely and cannot be healed until
Majin Benihime is resealed. Each of these wounds transfer blood in a vague
mist towards Majin Benihime, each fueling her form, creating muscle and
eventually flesh, getting considerably more powerful as she reaches her full
form. The speed at which she forms is surprisingly high, as it needs relatively
few attacks to absorb enough blood.
When she absorbed enough blood she reaches her full form, a demonic,
terrible, beautiful lady. At that instant she opens her eyes and show a
malicious grin. The opponent who gazes in her eye is paralyzed, making them
easy prey for her ultimate move: Blood tribute, Majin Benihime. Her claw
reaches out at incredible speed, piercing the opponent's body. It then proceeds
to suck out all remaining blood in the opponents body. As soon as the victim
is dried up husk, the absorbed blood transfers into the Bankai user's body,
closing his wounds and healing him completely.
To be honest I think kisuke's bankai is simply going to be a extremely hax, perhaps a one shot, ability. When kisuke wanted renji to help with chad's training he mentioned that his bankai could not be used for such a thing. Kisuke needed a more traditional bankai, one that chad would be able to fight head on against. In this regard. I was thinking of something along the lines of what aizen or shinji had as shikai or perhaps soifon's or kanane's bankai. Those are not traditional in the sense that you do not battle them directly and are somewhat abstract in principle. Soifon just has a nuke, it is not something you would fight the same way you would fight byakuya's, renji's or kensei's bankai. Aizen and shinji's ability just mess you up but you can't actually match your power against them. Kanane's bankai in a similar way just messes you up but does not give in itself a power up for the user which could be fought head on. At least based on what we have seen so far, kisuke's bankai is not going to be something huge which he can use directly as a weapon at least.
And the whole thing kinda makes sense in this particular way. Kisuke's benihime ability is kinda vague to say the least. Its not like he has the power of a giant or thousands of petals to attack with so far. his shikai just changes the shape of his sword and the ability of the sword itself seems to be a number of spells. I have the little theory that his sword does not have an ability in itself but rather simply allows the user to combine it with kido better than other zampakuto would hence the number of techniques urahara seems to have. Basically it works like a harry potter wand, it allows the user to efficiently channel power for specialized, more efficient, results. This would explain why urahara seems to be very good with kido, he needs it to make actual use of his sword. I guess the drawback would be that since the sword does not specialize in anything in particular it results in urahara himself not having exceptionally powerful shikai abilities, basically versatility vs specialization. On another note, if his sword works in this particular way, perhaps his bankai would allow him to use higher level kido combination with his sword. It would perhaps also make sense with what he told renji about his bankai. There would have been no benefit for chad to fight something which would basically combine level 90th kido with bankai lol.
I want to see his bankai so bad. It could be used for defense or maybe both to attack and defend. I think that he will have to be forced to use it in some type of battle that will be to tough for him or something like that
i know this is a old thread, and sorry for responding, but i have a theory. I think maybe the two kids are his Bankai. Jinta being the "Crimson" and Ururu being the princess, the true power only released when they both combine.