What did Blushweaver achieve? In fact, she Returned in the first place to be involved in this ending as well. One thing to note about the Returned coming back is that they do see the future, but when they Return, they aren't guaranteed to be able to change anything. Before her Return, Blushweaver was a powerful merchant in the city, and very well known. She was assassinated after denouncing a group of dye merchants she'd worked with for their deceptive and criminal practices. Her testimony ended with them in jail, but it got her killed. That's how she earned the title of Blushweaver the Honest (which, if you'll remember, she eventually got changed to Blushweaver the Beautiful).
She Returned because she didn't want T'Telir to fall to the invaders she saw taking it after Bluefingers and the others caused their revolt. That was why she gathered the armies. While she didn't succeed in her quest as well as Lightsong did, she did help out quite a bit. I think she's pleased, on the other side, with how things turned out.