According to the wiki...
Conviction is a class resource for the Cleric that is generated by certain abilities based on specific criteria.[1]
Conviction is a class resource we came up with for the Cleric specifically. Certain abilities will generate it based on certain criteria; and as Steven was saying there, you can either use it to heal an ally or you can use it to do damage to an enemy and generate conviction, which will then help you in the future heal for more. So, kind of what Keenan was saying about predictive play being an element, not just reactive: that would be the one of the predictive aspects of the cleric just setting yourself up so that when things start looking a little rough, you've prepared that in advance by not healing as much early on, and paying off later.[1] – Tradd Thompson
In the tank showcase we've seen that
they also have a "class resource" named Courage. Staking to improve mitigation, I think. (Wiki hasn't been updated yet and I'm too lazy to rewatch the video at the moment)
But what of the other archetypes? Do they all have their own class resource they can stack to improve their skills? We haven't seen anything for the mage, fighter and ranger but it could simply be because it wasn't ready at the time.
Can mages stack... Concentration?
Can fighters stack... Feats or Manoeuvres?
Can bards stack... Harmonies?
Can rangers stack... ?
I'll need help for names if this kind of mechanic is really for all archetypes. Any suggestions while we wait for official revelations on the subject?