Do you like throwing dudes?
Do you like having a 14" melee threat range?
Do you like not having wings and grievous wounds?
Do you hate having snipe to auto damage single-wound models?
Then Fyanna is the Ravens of War solo for you...
In theme she just seems redundant to me. She wants to track down and kill other solos or single wound infantry models. Just like every other model in Ravens is capable of, most of which from 12" away.
The tech you can leverage with her is throwing small based fodder models into small based casters and getting off a cheeky knockdown. Corner case though, not many people should let that happen. But her threat range might be surprising to most and catch them off guard.
She can be a weapon master versus living beast in a them that clearly isn't saturated with high damage attacks. It's not something to write off.
Lastly beat back could push a contesting solo out of range for an easy score. But unless it's a paladin I think she has just as much ability to kill it. Unless she can actually push models with a larger base than her. But I don't think she can.