1. When swapping gear sets during a lag spike, the gear in said set will grey out and become unable to equip. This requires a relog to fix.
2. Swapping weapons ridiculously fast can trick the game into thinking you have both equipped at once (Very abusable)
3. Using CrowdControl Immunity skills during skills with a cast time allows the skill effects to occur but does not put the skill on cooldown (Hunting Ceremony, Warlord Befalls, Light of Fortitude, Dragon God's Vengeance, Netherbomb, Annihilation Sphere, etc.)
4. Some ingame items can be used to activate skills and soul skills that are on the hotbar of non-activated mastery pages, allowing players to use skills and soul skills that aren't learned.
Will test other known issues when next online.