It would mean taking even longer to reach the cloud cover, but by making sure to hold her wings lightly when he moved in to strike, she could avoid him doing any serious damage. Tucking them in would be even better, but Joker moved so quickly that it would be too risky a proposition. If she tucked them in too early, she'd lose more altitude. If she tucked them in too late, her muscles would still be taut when he struck, and he might actually injure her. No, keeping them loose was the best way to approach the engagement.