I guess we should decide on likely CR to figure that out. What do you think? I'm not so good with high-powered critters.
Me neither.
Well, looking through the Epic SRD monsters, she resembles the
LeShay, who has similar two-weapon-fighting, SLAs and charm ability.
The LeShay has more HD, better ability scores and its hit points, saves and charm DCs are a
lot better (825 hp, Fort +29, Ref +44, Will +35,
charm DC 53 versus the
Hawk Lord's 277 hp, Fort +23, Ref +30, Will +24,
charm DC 35). The LeShay's Initiative is higher, too.
The hawk lady has the flight advantage and a better AC.
I'm thinking the LeShay is better, suggesting the Hawk Lady should be a few CR lower. She's got 13 fewer HD, suggesting 3-5 CR lower. The lower stats might be worth another CR, suggesting Challenge Rating 23-26.
Of course, once we give her magical gear that might well make a CR-worthy
difference, but currently my gut tells me she's roughly CR 24, maybe 25.
I have no idea whether she'd work that way in play, though.