Envy, Marsolit, the Borealis. Although he was the Original Sin that I used the most, his combat abilities weren't standing out among the Sins at all.
Maybe some people would think that this was because Marsolit was too young. However, an undead's power typically depended on the soul core. In his case he used a Semi God level core, someone incredibly stubborn on obtaining revenge. His soul's starting point was extremely high already.
All this time, what limited his combat strength the most was actually the Original Sin that he represented—Envy.
The Original Sins were my own soul shards. My own understanding of the Original Sins determined their abilities. Out of all the Original Sins, Envy was rather unique.
Envy was the Original Sin with the least negatives. In fact, most of the time, Envy could even be considered a positive emotion to possess. From a certain standpoint, its positive worth exceeded its negative worth.