#siddham script

The Yevon script seen in FFX (top image) was inspired by a form of Sanskrit called Siddhaṃ script (bottom image), which is used in one of the oldest and biggest Japanese schools of Buddhism - the Shingon Buddhism.

The letter A of the Yevon script alphabet represents Yevon (you can see this symbol repeatedly throughout the game), while the letter Z represents Sin.

An important practice for Shingon Buddhists is “meditating on the letter A”.

Therefore, this letter has a profound meaning in both scripts.

Info and image source: https://finalfantasy.fandom.com/wiki/Yevon

https://id.m.wikipedia.org/wiki/Aksara_Siddha%E1%B9%83