I think if were mothing away from unique buffs/debuffs we need more of the in the game for more variety...
https://wiki.guildwars2.com/wiki/Buff
What could be more new minor/mainor (de)buffs added to the game for more variety?
Devs can also look at other games like gw2 that uses a similar system and things like
Aegis
Alacrity; Increase skill duration or
Reduce skill cost
Quickness
Regeneration
Resolution
Blind
Slow
Confusion
Vulnerability to status effects