If you even loosen and retighten the screws holding the blade to the bed, the spring steel blade will probably take a different shape and it will be absolutely essential to regrind it. For practical purposes think if the blade and bed as a single piece - separating them is going to cost you machine-shop time to get your mower working again.
The job you can do at home is touching up the front vertical face of your blade without removing it from the bed (and usually without removing the bed from the mower). The top edge of the front face of the blade constitutes the cutting edge. With some skill and care this minor sharpening process can be done as often as necessary at home or on the job somewhere - just make sure that the front face of the blade remains perfectly straight and exactly transverse to the mower, not hollow-centred like an old cut-throat razor that's been badly sharpened. As soon as you go beyond that, you need fairly serious workshop equipment and it is going to cost you.
