Going by what Matt posted, it seems like possible grounds for a content revision. (Mr. Burns probably has a durability feat from surviving all that wealth falling on him, for one.)
Frankly, though, I'm voting Izumi, High Difficulty.
Going by our current profiles....
She at least has the strength to lift a pen, or even a kitten.
Mr. Burns struggles to crush an ant. His doctor claimed he could be injured by a light breeze, & he's been shown to become dehydrated after sweating a single drop, & exhausted from running a few meters.
If an ant can knock him over when he's trying to crush it, I'd think a woman with a strength to write with a pen can probably do similar.
But at the very least, her ability to lift at least 1 kitten suggests even if she has less stamina, she's probably stronger, & she doesn't get sent flying by mere light.
I can see the case for inconclusive, but I think Izumi, high difficulty, since she might be able to harm him more than he can harm her, so long as she doesn't collapse first.
Also, are we SURE a park is the most fair location for the battle? Dirt, possible bugs, stones, blades of grass, possible unimpeded breezes.... Is there water about? Can either of these 2 swim?