In the Origin Refinement Stage, a Martial Spirit imbued a certain attribute in the cultivator's Origin Essence. For a cultivator with a Fire Martial Spirit, his Origin Essence would have the attribute of fire, allowing him to unleash attacks that burn his target.
A Trash Martial Spirit, as the name implied, didn't give any attribute to the cultivator's Origin Essence. This was why they had no future, usually treated as servants and guards by the Clans and Sects.
Above it was Human Martial Spirits. If a cultivator had a Tiger Martial Spirit, their Origin Essence would have its property, allowing them to obtain all the abilities a tiger possessed. Scent tracking, lithe body, graceful body balance, running speed, etc.
Anything and everything a tiger was capable of, they too would be able to do so. If someone obtained a Rhinoceros Martial Spirit, they would have exceptional defence, unbreachable by most attacks.
