I see your point but if you compare it to a character like peacock her blockbusters seem to deal more damage the higher the move cost.
With Eliza her khepri sun is the lowest cost and when tested did the most damage out of all her blockbusters and Cerebellas DAF only seems to do 10% less damage then her Unblockables which kinda makes them less valuable since you can use DAF twice before you get your unblockable.
Yes, but Peacocks blockbusters don't do anything extra, they're all just "Hit the enemy a bunch of times"
Most of Eliza's Sekhmet powers are underpowered compared to those of other characters, except that they activate Sekhmet mode, which can do a ton of damage. If I get all three charged up it's not unusual for me to be able to take down 1 and a half characters worth of life without fear of retaliation. And they're cheap powers! On Diva Intervention they're particularly bonkers, because they recharge themselves.
So Lady of Slaughter could be balanced with a similar mindset, though one that really does not work as well, because tossing your enemy across the screen and making them temporarily invincible by knocking them down is a garbage way to start Sekhmet mode.
Nekhbet Breaker, I don't know what to say, but I like it and still use it a lot because burst damage is at something of a premium in this game. But by that justification, Diamonds are Forever should also be less good.
I don't disagree that the powers could probably be looked at, but I thought I'd give a shot at explaining why they cost what they do.