Seraphim were specifically designed to replace Grand Corsairs in the Three Great Powers dynamic.
They are clones of the ancient Shichibukai created using the Lineage Factor, but they are larger in size compared to the original people they were cloned from. In particular, S-Hawk – the Seraph based on Dracule Mihawk – exhibits an incredibly destructive level of swordsmanship, capable of splitting mountains in half, much like Mihawk himself. Pythagoras speculates that it could be a property of the lineage factor, which could potentially pass on the memories of skills acquired by original individuals to their seraphim counterparts.
Seraphim also appear to have been modified to possess lunar appearance and characteristics, including the ability to burst into flames. Like natural Lunarias, Seraphim are able to become much faster when their flame is extinguished, but they become more vulnerable to attacks.
Seraphim undergo an accelerated growth process and are infused with a substance called Green Blood which can be instilled with a Paramecia user’s bloodline factor, allowing that unit to emulate said user’s Devil Fruit abilities as S-Snake’s Mero Mero no Mi, S-Shark’s Sui Sui no Mi, and S-Bear’s Nikyu Nikyu no Mi.
Due to all the technology that must be invested in creating and maintaining them, Seraphim are considered extremely expensive to manufacture. This can be attributed to the fact that lunar DNA is hard to come by, as are the materials used to create them. Thanks to their many unique characteristics, they are considered by their inventor, Vegapunk, to be the highest echelon of science imaginable, which he even calls the strongest form of humanity in the history of the sea.
Although artificially created, their biological nature means Seraphim are apparently able to age and therefore become stronger as they grow. They displayed enough strength and skill to force even one of the Four Emperors, Marshall D. Teach, into a defensive position, just after effortlessly defeating myriad of his subordinates.
Additionally, thanks to their moon-like traits, they seem to have great resilience, which was noticed by the Gorgon Sisters, who claimed that the Seraphim involved in the siege left the island without a single scratch on their bodies. Their young age can also prevent enemies who are reluctant to fight children from attacking them. Helmeppo would later deduce that sending a single Seraph against the Blackbeard Pirates would be enough to at least save Koby, who was captured.