Board Thread:General Discussion/@comment-4008620-20190228152351/@comment-5398287-20190307203548

Isshin couldn't use his Bankai because his injury prevented him from properly controlling his Reiatsu, which is the basis for a lot of techniques as it is. Also, no, as far as we know his Zanpakutō is not a fire-type, it just LOOKS like one due to the energy it gives off in Shikai resembling flames, like Yamamoto's Reiatsu. If anything, given the similarities between Ichigo and Isshin's powers as it is, I would expecting something similar to Tensa Zangetsu, not this...blood evaporation stuff.