Sephiroth has multiple forms in Final Fantasy 7, but Safer Sephiroth is his most dangerous and has the most connections to Kabbalah writings. The danger of Safer Sephiroth goes beyond game mechanics and into his story arc as he goes from respected SOLDIER to global threat. Since it's his final form, Safer Sephiroth is the culmination of his resolve to take back the planet with Jenova.
Sephiroth was considered a hero when he was a SOLDIER 1st Class, but revelations regarding his origins started his transformation into a villain. He believed that his mother's name is Jenova, but learning about the Jenova Project and seeing the monsters created by it left him shaken. Sephiroth in Final Fantasy 7 Crisis Core reads what he can find about the project, coming to believe that he is the last of the Cetra with Jenova being part of that race, which leads to his desire to avenge his ancestors.
Sephiroth's past and his anger relate to his final form of Safer Sephiroth. The form of Safer Sephiroth is similar to that of a Seraph, but with an extra wing to total seven instead of six. During this fight, "One-Winged Angel" plays, and some of its lyrics translate to "Burning inside with violent anger." This translation relates to the meaning of Seraph, which is Burning Ones. When these details are looked at together, they hint at the possibility of Safer Sephiroth being a mistranslation between the English and Japanese versions of Final Fantasy 7.
Final Fantasy 7's Penultimate Boss Was Likely Meant To Be Called Sepher Sephiroth
Both Sephiroth and Sepher Sephiroth have many ties to writings in the Kabbalah. Sephiroth's name is likely derived from the Hebrew word Sephirot, and the Sephirot are seen as the ten forms of God's manifestation in the physical realm. This reference is especially fitting considering Sephiroth is trying to become a god at the end of FF7, and his Safer Sephiroth form seems to put him somewhere between a Seraph and the Sephirot.
Despite the changes being made in FF7 Remake, Sephiroth's relation to Jenova is the same. However, his goals remain unclear, and Cloud's first encounter with Sephiroth resembles FF7 cut content, which might mean that Safer Sephiroth could be renamed if it is the result of a mistranslation. Alternatively, it's possible that Safer Sephiroth won't be included in FF7 Remake at all given the different direction its taking, and because it seems that Sephiroth could have new goals in the remake that make his most dangerous form from Final Fantasy 7 unnecessary.
