'Norexam' is supposedly the canon name for the class of ship we call the 'Valdore'. Valdore was only the name of one of the ships and commanded by Donatra alonside the Enterprise-E against the Scimitar. Because of the way Paramount seems to treat canon material, we have not had good schematics or any other clarification on the ships abilities, history, etc.
We just saw two of them show up to help the Enterprise-E.
What I find funny about people's reaction to the Norexam class is their opinion that they suck; largely based on their performance in the movie (and this view seems to be of the majority of Star Trek fans). Well, look at it this way: the Scimitar only wanted to disable the Enterprise... without harming Picard. The Norexams were just getting in the way, so had to be eliminated as quickly as possible; which they were. That meant they took the brunt of whatever the Scimitar was throwing out at em, while the Enterprise-E was just getting a wrist slap in comparison. The Enterprise-E and the two Norexams were dishing out all they had against the Scimitar; and still at the end of the battle, it's shields were only down to 70%!
Some people just watch movies without actually seeing I guess.