User blog comment:Xilinoc/Ch. 564 (Mask is too fabulous to live)/@comment-24099400-20140115223446/@comment-11051098-20140116191121

Since Ichibei knows the name of every Zanpakutô there is, he could have told Kenpachi his Zanpakutô's name, and the same result could have been achieved without Unohana's death. But I suppose Kubo has a reason for every little thing he does.