User blog comment:Skitzo1/Is it possible Getsuga Tenshō is a technique not an ability?/@comment-6963992-20130521223240

We've never seen a Zanpakuto use an ability in a sealed state and if Isshin was sealed then it would be the exact opposite. Ichigo would probably never get another technique because he didn't have another ability to begin with(but that's speculation).Besides he is a melee type and some of those don't have 1 ability.