I cannot let you pass!
Spathi (called Sword in the PlayStation 3 version of Final Fantasy X HD Remaster) is summoner Isaaru's Bahamut, who is the last aeon called during the battle against Yuna in the Via Purifico at Bevelle.
Bahamut cannot be called to fight against Spathi, so he will sit out this one. Ifrit or Ixion are the best of the rest, and preferably one or both has a full Overdrive gauge. Spathi will not attack but starts a countdown until he uses Mega Flare, at which point shielding is recommended.
Spathi is Greek for "sword". Spathi's original name, "Tsurugi", is Japanese for "sword".
sword is a blade weapon used primarily for cutting or thrusting. The precise definition of the term varies with the historical epoch or the geographical region under consideration. A sword in the most narrow sense consists of a straight blade with two edges and a hilt. However, in nearly every case, the term may also be used to refer to weapons with a single edge (backsword).A