To be honest, these questions have never been interesting for me. But I needed Oscillating multi tool and this forced me to read a review about DeWalt DCS355d1. I know nothing about such tools and a review can hardly help me but it helped and I bought a good device
WOW, that would be hard to answer since everyones idea of an average blade of grass is different. I would think about the same weight as 3 average feathers.
To answer this question you would have to say "typical, average" grass blade for the common name or specific grass species name. Then the leaf area index and leaf (blade) width. The question needs better definition. Such as what is the average weight of the big blue prairie grass blade with a leaf area of 0.2, ~2mm width and 4ft length.