'Will'. The same sort of ability I use to sense others when I'm blind can coat my body to act as armor. It's used to enhance my physical attacks.

However, it can also work to prevent my strength from causing you real harm. If I focus my will and weaken it enough, my punches won't strike you with full force at all.

[This was supposed to be comforting, he thought.]

However, I'd much rather ease you into training rather than exchanging blows with you. For starters, you'll be the only one attacking.