This is on dummies, so it might work differently on actual enemies, but the text says
Dodging while blocking increases dodge range by 20%. Dodging while not blocking increases the power of Kerillian’s next strike by 10%.
In actuality, the 10% power buff doesn’t apply only to the next strike but to all strikes during the ~2 seconds timer the buff is active for.
I don’t think it is a bad thing, even though it is akin to a flat 10% power increase, but there is a discrepancy between the talent’s text and its behaviour.