Thanos's ship was still the Sanctuary I he had seized from the Marauders long ago. Cloak had just located it in space, somewhere in low orbit around Titan.
It was an armed cargo ship. After all, the Marauder gang Thanos had once belonged to had been pirates, and pirates who killed and plundered naturally needed cargo holds.
Yet this ship, which looked like the letter "H" from the front and like a section of construction-site girder from the side, was not entirely useless. After Thanos killed the Captain and all the troublemakers before taking over as leader, Sanctuary I underwent comprehensive modifications. Its defenses and firepower rose to an astonishing level.
Other than races whose technology matched that of the Three Great Empires, almost no one's weapons could pierce its shields. In the comics, Thanos had once set it to autopilot and leisurely enjoyed the scenery while under attack from hundreds of thousands of Alien warships.
It was also equipped with a Planet-Killing Weapon, a ballistic weapon that looked like a missile but functioned more like a nail.
Once launched, it drilled into the target planet's core, causing the Anti-Matter in its warhead to react with the core and destroy the planet in a stellar-core explosion.
It had no conventional weapons to speak of. The people aboard were all ruthless killers; what use did they have for those?
Thanos's usual method of invasion was to force his ship through a fleet's attacks and land it, then release the Black Order and his adopted daughters, along with a massive swarm of biological or mechanical minions, to slaughter an entire planet.
Of course, the main killer was still Thanos himself. He could fire Cosmic Energy from his hands and eyes. It was the result of Death's Genetic Modification of him, somewhat different