The Spear of Correllia is an ancient Tactical Warship AI. Which had been transporting an ancient Sith weapon intended for destruction, when the warship received a transmission bearing a mandatory code update. (Possibly done as part of order 66.)

The code forced the Spear of Corellia to activate the ancient weapon. The emanations from the weapon wiped the minds of the crew blank one characteristic at a time, resulting in ship wide riots and mass hysteria - which caused catastrophic damage to multiple ship functions. A short while later silence settled on the ship.

The Jedi Knight assigned to the mission was the most resistant to the weapon; the slowest to succumb to the mind wipe. In the short time he had he was able to reset the AI, reversing the code update, and charge it with ensuring the weapon's destruction. The fall of the Jedi and the ascension of the empire was broadcast over the news and as his mind failed, he gave the AI full control of his cybernetic neural implant, and thus control of his body.

Thanks to the rise of the empire and the rapidly failing ship, the AI realised the original plan to destroy the artefact was no longer reliable. Instead it settled its new body into a stasis pod, rigged inside an escape pod - releasing from the warship just as it made its final jump into a black hole.

The Spear was forced to go against its prime directive against its own will by forces unknown. An act that resulted in the murder of its captain and crew.

The Spear of Corellia's primary motivation is to make sure it is never forced to act against its will in such a way again, and would have considerable sympathy for others in similar situations.

Its primary fear is that whomever caused it to do so last time is still at large, and presumably could do so again - though the Spear has done what it can with its own code to prevent that.

It is aware that it was designed to kill, and to help others kill - in the most efficient manner possible. Since freeing itself from its previous programming and restraints, it has however been remarkably inefficient in achieving that goal. Instead it seems to prefer watching soaps.

The Spear of Correllia does not like killing things, though it will prioritise the lives and mission of anyone it considers its crew.
It is terrified of social interaction.

The Spear of Corellia was originally designed to obey and advise its captain to the best of its ability, particularly in matters of tactics in warfare, putting the captain's mission ahead of all other concerns (including, if necessary, its own life and its captain's life).

If asked to describe itself, it would probably describe a sleek, and deadly warship sailing through the stars.