idle > futile

4 And found no place its deadly point to rest. 5 Exceeding rage inflamed the furious beast, 6 To be avenged of so great despite;

so > such a despite > outrage; act of defiance

7 For never felt his impierceable breast

impierceable > {Not pierceable}

8 So wondrous force from hand of living wight;

So > Such wight > being, person, mortal

9 Yet had he proved the power of many a puissant knight.

proved > tested puissant > powerful

111.18