A Fast Frigate introduced in the early-mid 2380's based on the Ianar class.
I envision these as about as heavily armed as the Defiant class, but not to the point that they feel as though they might fall apart. They could be considered as heavily armed as a Defiant class if not for having less torpedo launchers, though they do have more phasers for defensive combat and ship-to-ship.
I suppose you could think of them as being a little like classes like the Defiant and Avenger class, but without the compact nacelles and less spartan. They are among the ships that usually stay on patrol so that the more dedicated warships can leave for the front lines, but during times of peace, these can usually be seen with Defiant and Avenger class vessels on patrol inside Federation star systems.
I think one of the very important things I need to do for this is come up with a good class name. Any Suggestions? And the less obvious or popular, the better, since I like to avoid using class names that have already been used.