Ok, I've never known what luck does on any RPG game but haven't really been fussed.
But now I'm playing through Final Fantasy X again and I control attribute growth I want to know what it does.
I've seen conflicting theories on the net. Does anyone know for certain?

One FAQ says it improves stealing, while another says it does nothing for stealing.
Another says it increases both evasion and accuracy.
So what does it do?
Just so I know who to use the Luck/Fortune Spheres on.

And for future reference does luck do the same in all other Final Fantasy games?

The Luck stat as different affects depending on which Final Fantasy you are currently playing. In Final Fantasy X, Luck affects chances of critical hits, evading attacks, and accuracy. More information can be found in the following link below.

http://finalfantasy.wikia.com/wiki/Luck_%28Stat%29

I like how in IX the luck stat 'appears' to affect the rate of being inflicted by a status ailment. I presume this means that Square have never explained it?

But going back to X, you need luck for the critical hits on the dark bosses. Faff.

I don't think they ever explain, they just keep us guessing lol. It's like certain damage formulas, when some people want to know how it works, it's not always clear.
Thanks for the link anyway. At least it gives me an idea of who to use the spheres on.