SeraphimSeraphim are referred to in different respects depending on what religious background you are looking at, but the traditional Christian beliefs seem to fall closest to Kratos' role as a seraph in the story. Therefore, this page will be somewhat based off of that religion. "Seraphim" is a holy name that means "those who kindle or make hot" (Dionysius). According to my computer's dictionary, the definition of a seraph is:
ser•aph [noun] plural: ser•a•phim - an angelic being, regarded in traditional Christian angelology as belonging to the highest order of the ninefold celestial hierarchy, associated with light, ardor, and purity.The status of a seraph is higher than that of an angel, which is a race that is pretty "high up there" in Tales of Symphonia as it is. Therefore, Kratos, being one of the four Seraphim of Cruxis, has a high "social" rank. He has angels under his complete command in Derris-Kharlan, whom even elves are below. Though it is never said just how long Seraphim can live in Tales of Symphonia, Kratos is already over four thousand years old, so I think it is safe to assume he's probably going to be around for quite some time. According to the Christian religion, Seraphim are immortal. Kratos wishes to die for a good portion of the game, believing he has been alive for far too long, so if it were a simple task to die, he probably would have done so some time after losing Anna and Lloyd. Since he almost died after releasing Origin's seal, however, I don't believe he's exactly immortal, since he has the potential to die. He probably can just live for thousands of years accompanied with great power to make it difficult for him to die easily.
Seraphim are said to be mainly concerned with keeping divinity in perfect order. Though he isn't exactly interested in "divinity," he wants to fix the chaos the two worlds have fallen into. A medieval writer named Dionysius wrote,
The name Seraphim clearly indicates their ceaseless and eternal revolution about Divine Principles, their heat and keenness, the exuberance of their intense, perpetual, tireless activity, and their alleviative and energetic assimilation of those below, kindling them and firing them to their own heat, and wholly purifying them by a burning and all-consuming flame; and by the unhidden, unquenchable, changeless, radiant and enlightening power, dispelling and destroying the shadows of darkness. (Celesial Hierarchy, chapter VII)Though the connection is a bit shaky, Kratos did spend quite some time looking for a way for humans to wield the Eternal Sword (or at least since around the time he met Anna). His purpose was to reunite the two worlds, which would be causing an "eternal revolution" of sorts. Unfortunately, Kratos did not have a strong resolve for most of his life, and therefore couldn't really be said to have a ceaseless flame kindling beneath him the whole time. The only sort of holy being that Tales of Symphonia makes reference to is Martel, but since Mithos is the leader of Cruxis, you can look at Kratos' relationship to him as a Seraph to God. He carried out the will of Mithos, whose true intentions were to rid the shadows cast over half-elves. I know it's quite a bit of a stretch, but some light symbolism may be there. Needless to say, Kratos is quite powerful and does end up "dispelling and destroying the shadows of darkness" with Lloyd and the others.
1. Dionysius the Areopagite: Celestial Hierarchy