I think this one is about the fear of "falling", or falling in love. The air catcher basically is just a parachute and that's metaphorically how he always caught himself before he could fall too hard for someone. However, this person has now completely knocked him out and although he's afraid of falling in love, he doesn't want it to stop ("you've stolen my air catcher, and I don't know if I want it back"). He knows that if he loves this person he opens himself up to vunerability and is allowing the possibility of getting hurt ("tools to destroy my heart").
I think this one is about the fear of "falling", or falling in love. The air catcher basically is just a parachute and that's metaphorically how he always caught himself before he could fall too hard for someone. However, this person has now completely knocked him out and although he's afraid of falling in love, he doesn't want it to stop ("you've stolen my air catcher, and I don't know if I want it back"). He knows that if he loves this person he opens himself up to vunerability and is allowing the possibility of getting hurt ("tools to destroy my heart").