Dean reaching for the knife did worry her just momentarily, It twitched in her hand before she handed it off to Claire not even entirely worried as to what it might eventually mean. And she watched as she sliced across her forearm. That wouldn't do it. It wasn't enough especially with her healing ability.
"Twi..." she started but trailed off as she realised Claire already was twisting the knife into her arm, and likely didn't want to hear advice on getting blood out of herself quickly from her of all people. But she did know what she was talking about on that score.
She moved in a little pressing her palm onto one of the worse wounds Claire hadn't reached yet. Winchester blood on her hands, ironic of course that it was this Winchester and not the one with the power in his blood, but she knew that was for the best, and so she pressed her hands against the wound to keep him as stable as she could. It wasn't worry for Dean entirely, she didn't think they'd ever be friends but she knew he was important to people she cared about even if she wasn't supposed to care. And she supposed he'd offered her chances she'd walked away from, spat on even. And now, the simple act of handing over her knife could be a start to maybe someday making it up to him, to Claire. Her eyes fell on the wounds curiously. He didn't have long.