"Do not pray to me for victory, or even for survival. All I offer is a fair shake. That is the limit of my domain.
"The boon of my domain is that, if you manage to parlay that fair shake into victory, you and I are not debtor and patron, but partners in mutual glory. Wouldn't you rather shake your god's hand than kiss his feet?"
JOUST - GOD OF REDOUBLE
Joust probably originated in the middle days of Merakor. The record of a duelist obsessed with finding equally matched opponents and setting them onto fair battlefields is a theme all up and coming heroes wonder about. "I would have won IF...", or "They had the uphill advantage", or "I wasn't feeling all that good"... as excuses for failure proliferate, a select few rise up and seek out rematch.
Joust is depicted as a duality, like the white and dark wings shown here. However, levers and fulcrums and scales are also popular ways of showing Joust in a non-aligned way. No one is really sure who or what Joust is, or even if Joust is part of the pantheon of Heaven. What is known is that anyone can be touched by Joust when in the throes of seeking a fair shake, an even match, or trying to re-challenge some past loss. Some of those touched, become clerics and begin preaching about Joust, enough so that there are shrines and even temples to this god.
If you read the epic battle between Drizzt and Artemis, you've seen Joust. If you felt a twinge of envy when those you know get promoted, or if you ever felt someone given credit for your work and wondered why it isn't you... that's Joust. When challenged with such things, most people shrug it off. A few though, do not. They take it as a personal challenge and redouble their efforts to earn it and have <whatever it is> as their own triumph.
Worshipping Joust is an informal affair. Most adventurers and commoners alike will swear by Joust. Something good happen to an enemy, it must be Joust. Something lucky happen for you? That was Joust too. As such, there is no god in the Forsaken Isles that is more profaned than Joust. Meanwhile, Joust's true worshippers watch, study, and seek out epic adventure to set right the wrongs of the world however they might. When defeated in combat, Joust worshippers come back as strong as they can. If the floor was wet and it caused them to slip, they will treat the quest to find slipproof shoes as an adventure unto itself.
All Joust worshippers seek out a foil... someone against which they measure their current progress, as well as an aspirational foil, who they wish to someday become. When satisfied with their life's aspirations, or when facing hopelessly unfair odds, Joust rises up in their heart and grants them courage. This is the stuff from which true heroes are born.