What's interesting is that Yamamoto implied that once Fach's sword was destroyed, he wouldn't be able to recreate it (at least not in the same battle). It is quite interesting, because this means that their better weapons are crafted by the user that pours his reiatsu on it through days, weeks, month or years, in similar fashion how Ishida was able to create a stable, solid bow from the glove thanks to his training. It was shown that when he first started training with the glove, he wasn't able to pull out the solid form, but after training it day and night, it finally gained a proper form. Ryuken, Uryu, the Stern Ritters have showed that they are able to create a more solid weapons, for now it wasn't revealed if they have their own blacksmiths (Ryuken himself was able to create Soul Cutter-arrow, but it is unknown how), or if they polish their weapons with their own energy until those gain proper forms.
Byakuya didn't recognize GT, but it's likely that no many people would recognize WE either, since in this case it was a final technique of the Noble Kuchiki Clan that needs to be mastered in order to become the new Clan Head. Assuming that Byakuya's bankai hasn't returned, he might be teaching it to Rukia (beside Bankai of course), since it seems to be the strongest technique he posses, quite similar to FGT, since both of them uses all the energy for one attack (though FGT is way more extreme).
The name fits very well with what the Shiba clan does - taking care of transport for the RG, by literally piercing the heavens with a fang (pillar).
So, is Ishin an unlicensed doctor, or did Urahara prepare a fake license for him ?