I've written up a race for an awakened panther so we can use the standard character rules to make this companion. Below is the new race for awakened great cats.
Awakened AnimalsAwakened animals are regular animals that have been granted a human-level of intelligence by magic, divine intervention, the sheer power of nature, or some other form of magical change. They can advance in class levels like any other PC race, and follow all other associated rules. While they have the knowledge needed to understand the use of tools, weaponry, and other humanoid creations, they are restricted in their use by their physical form. Each type of animal has it's own set of racial abilities.
Awakened Great Cats
Great cats, such as lions, panthers, and tigers, which have been granted a human-level of intelligence by magical intervention.
Thick Hide: While unarmored, an awakened great cat has an armor class of 6 . When factoring armor class while wearing armor, start from the standard base armor class of 9 .
Natural Weaponry: Awakened great cats are capable of attacking with claws and bites. The cat may make 2 claw attacks as an action, each dealing 1d4 points of damage on a hit. If both claw attacks hit, the cat may pull the enemy in for a bite attack, which deals 1d6 damage on hit.
Darkvision: Awakened great cats can see in the dark out to 60 feet. This ability does not penetrate natural darkness.
Keen Senses: An awakened great cat is only surprised in a roll of 1 on a d6 in combat. If the Referee calls for a skill check associated with hearing or vision, such as the Notice and Search skills, the cat increases his or her skill die by one step.
While written specifically with Heroes of the Sundered Chronicles (an S&W variant rule set) in mind, this race will work perfectly in S&W or other compatible OSR games. You'll have to either ignore or adapt the skill bonus from Keen Senses.