He's not as good at noticing when people are holding back their strength from him as others in his profession might be, especially in situations like these. Harley is fun and he's having a wonderful time flirting with her - why would he be paying attention to her strength when it's not affecting him right now?

"Good, then it's all yours." He grins and offers his arm to Harley again as he stands. "We'll have to find a few more that make you feel good. I don't want all of your outfits being made of the same fabric. I can make lots of things out of a single bolt, but that gets boring after a spell and I most certainly am not allowing that for you."

Or anyone else, but he's a little too distracted to mention that to her right now.

He stops them a few tables over when the sun catches on a sequined fabric among a large pile of other blues and greens. Grinning, he tugs it out and shows it to Harley. "This screams 'mermaid' for some people, but I look at it and think 'forest nymph' for you. What do you think?"