I'm new here, so please forgive me if this has already been discussed. Does anyone have a theory about who in the tower embassy party stole it? Could Taim have somehow gotten hold of it? Or is it unimportant and never to be heard about again?

Hey welcome to the forums.

 

For some reason I think that it was not stolen but mis-placed. If memory serves me correctly, he had the angreal later on in Knife of Dreams. it was in his coat pocket when the Embassy met him before snatching him up and he was not wearing his coat at the time.

Nope its gone, It will be interesting to see if it turns up and who might have it.