Can we also take a look at his 1 Cursed Strength? Fafnir in the support role has somewhat iffy peel IMO. His 1 is among the most skill intensive CC abilities for any Guardian. There are any number of changes that could be made to enhance the ability, but I think simply lowering its cooldown by a few seconds would be the easiest thing to do. I mean if we look at other Guardians for a moment.

Kumba Groggy Strike 10 second cooldown hits multiple targets

Ganesha Omh 10 second cooldown at max rank and silences multiple targets for longer than Faf stuns one.

TreeBoi Verdant Growth 12 second cooldown at max rank

Just a thought.