So I think I know who has Taln's blade.
Nalan.
This is in Ch 106
Nin held out his empty left hand. A Shardblade appeared there, different and distinct from the Honorblade he carried in the other hand. “I am not only a Herald, but a Skybreaker of the Fifth Ideal. Though I was originally skeptical of the Radiants, I believe I am the only one who eventually joined his own order.