@Fukaziroh
No one knows how it happened and I am sure Kimi herself didn't know it belongs to someone else.
That said can she still reverted?
I sincerely doubt an esper could do it.
An interference from Touma or magic side might be necessary to return herself back else she'll just get consumed and die or go berserk.
Or
That Honoka girl is somehow still alive which force Kimi into another state.
Next chapter we may see her "actual power".
Her power might be related to allowing oneself to get possessed or became a vessel of another being.
Else I have no idea what it was even about lol. Quite sure that hand of hers didn't got possessed when during the past event.