Lawn mower blades are meant to be somewhat blunt. Like a butter knife. Too sharp and the blade will chip away on the harder materials.

I have a battery electric lawnmower. I found I got noticably better battery life after sharpening the blade to a near razor edge. Yes the edge is more fragile but it cuts the grass with much less resistance.

That I did not know. I still wouldn't stick a finger near one of course.