No offense, but maybe if you don't know anything about the topic you shouldn't answer? Because your spoiler doesn't apply to the question at all.
What happened to Umbriel:
Attrebus and Sul retrieved Umbra (the sword), and then plunged it into the Ingenium (the soul svcking machine that was keeping the city afloat). Meer-Glim was then able to mind-link with the trees (which were close relatives of the Hist of Black Marsh) and they were able to send the city back to where the trees originally came from. It's not said where exactly this is, just that it's another dimension and is rather jungly. Here's the description of it from the http://www.imperial-library.info/content/lord-souls-lore-notes:
“Far away, another man [Glim] and woman [Fhena] listened to a deeper, stranger music and watched the luminescent films they had named wisperills do their slow, colorful aerial dances, as if welcoming them. The trees hummed and murmured, not as before, but with the strength of the millions that spread out and away in the strange land, whose great boughs supported the island when it could no longer fly and helped settle it deep in boggy ground.”