He took her hand gently, and flexed the part of his mind that allowed him to heal others. At least, that's always what it had felt like. Like a muscle, only in the brain, a little pulse for a second or two, and then it pushed down and out of his hands, into whatever it was he was trying to fix. It didn't always fix whatever was wrong as quickly as he expected it to, but it had never failed him yet. He did it first before he even unwrapped her thumb. Actual skin-to-skin contact wasn't required, as through cloth worked, but skin touching worked best. He wasn't surprised to see the cut still bleeding when the handkerchief came off, but it wasn't flowing the same way as it had been, which meant they weren't both going to be covered in blood at the end of it.
He laid his palm over her thumb and let the healing energy go through him again. Once. Twice. "That should have done it," he said with a smile. He gently took his hand away, nodding down at her hand. "See if it still feels tender, though, and I can do more if need be."