Scimitar

The Scimitar was a prototype dreadnought, used by Shinzon in his takeover of the Romulan Star Empire in 2379. (Star Trek Nemesis)

Technical Data
The warship was very heavily armed, mounting a thalaron weapon capable of destroying all life on a planet in addition to numerous conventional weapons. The Scimitar boasted 52 disruptor banks and 27 photon torpedo bays, as well as primary and secondary shields. The Scimitar also carried a number of Scorpion-class attack fighters.

It's cloak was among its more impressive features. It was considered perfect by the standards of the day, emitting no tachyons and leaving no residual anti-protons. In addition, the ship could use its shields and fire its weapons while remaining fully cloaked. The Scimitar could also decloak select sections of the ship without fully decloaking. (Star Trek Nemesis)

History
Shinzon used the Scimitar to not only enforce his new position as Praetor, but also to back his claims to the Romulan Star Navy that he planned to launch a devastating attack on the Federation in 2379. However instead he found it necessary to pursue the USS Enterprise (NCC-1701-E) in hopes of kidnapping Picard and using him to reverse his cellular degradation. The Scimitar caught the Enterprise and engaged it and two Valdore-type warbirds in the fierce Battle in the Bassen Rift. All ships involved were heavily damaged, including the Scimitar after a successful ramming attack by the Enterprise. As his last act, Shinzon attempted to use the Scimitar 's thalaron weapon to kill the crew of the Enterprise, but an Enterprise boarding party successfully disrupted the Scimitar 's thalaron generator while it was powering up, destroying the ship. (Star Trek Nemesis)

Star Trek Online
In the Star Trek Online timeline, the Scimitar became the first of a class of powerful dreadnoughts that saw wide use after 2379. In the early 25th century, the Romulan Star Empire, the Romulan Republic, and the Reman Resistance were all known to have Scimitar-class ships. The capabilities of these ships relative to those of the original Scimitar appeared to be somewhat limited. (Star Trek Online)