Ninja

[Arkenne]

I thought auto attacks were every three seconds.

You can see the auto-attack timer on your weapon's description as Delay.
Some weapons have 2.48s others 2.56s and others even 2.64s

This is affected by Huton tho, so its almost 2 seconds per Auto-Attack.

It seems like for the sake of Ninki, NINs will be forced to go for the Relic/Anima weapon of SB, since its the one with the lowest Delay.