Yep. I took the blade off my 5 yr old Craftmans mower with Honda engine to sharpen. Long story short, I went to start it up several weeks later it was hard to start then surged quite a bit. I shut it down and tried to start it again. Cord was tough to pull once then couldn't pull at all after that. Frusterated I put it away. That's when I noticed the blade sitting on the bench.

What damage did I cause?

Should not be related.