[Flere821]

Originally Posted by Kuroi Hadou

Do those statements mean Fiamma is capable of doing the same things as the wielder of Curtana Original, and vice versa?

This get explained at the end of Vol18:

Spoiler for Curtana & Michael:

Fiamma can in theory do magic on the same power and scale as Curtana (ignoring the UK symbolism part) - but if Curtana tries to do something Fiamma can it'll self destruct, Fiamma has so much Telesma at his disposal if Curtana tries to channel that same amount it'll be destroyed.