Big, slow, old.
I took it in a little different fashion though.
I created this ship, it has more in common with a mining ship then a cruiser.
SO the story I thought up went something like this.
It's an old outdated mining ship, it has a massive hull mounted laser cannon that used to be use to blast large asteroids to pieces. Back during the founding of sirius companies needed to use whatever they could get, and blasting a large asteroid to pieces to get at it's core where the most minerals are usually found was the most feasible, and cheapest way to do it. Moving around, and moving far to search for more accessible minerals wasn't practical at the time. Thus the "Rock Hammer" was created. It was rugged, heavily armored and armed to be able to smash apart it's target and stake it's claim at the minerals inside. Since there was little shielding back in those days the hull was made 3 times the thickness of average mining ships today, and the power plant was designed for a vessel much much larger. Its only weakness was it's slow lumbering engines. This combination made it great at what it did, but with the advances in trade lane technology and better engine design and jumpgates, companies no longer needed to use whatever was nearest to their resource centers. They could move far and transport their mining operations to the easiest debris fields where resources are plenty.
The Rock hammer quickly fell out of love in the eyes of the Rheinland corporations who birthed them. Operating cost became to high, and renewing their Rock Hammer fleets would cost more then just building newer ships. So over time each ship was scrapped. Many of their massive hulls left derelict and floating in the places no one would normally look.
It wouldn't be until many years later these sleeping giants would see use again. Their new owners the Red Hessians. Seizing their sills at engineering, and a little bit of ingenuity the derelict ships had been captures, and repaired. Adding new shields, and updated weapons these ships would serve as the backbone of the Hessian fleet. Each ship is slow, and handles poorly but the massive mining laser, fined turned could turn even the most advanced warships into a smoldering slag deposit.
