maugre > notwithstanding (this word is used by Spenser more or less catachr. as a general imprecation or indication of ill-will: here the sense might be taken as "like it or lump it")
5 Nor longer stayed for the other to reply,
stayed > waited
6 But with sharp spear the rest made dearly known. 7 Strongly the strange knight ran, and sturdily
ran > [galloped towards her with lance extended; cf. 307.38:8] sturdily > courageously; with reckless violence
8 Struck her full on the breast: that made her down 9 Decline her head, and touch her crupper with her crown.
crupper > {The strap fastened to the back of the saddle and passed under the horse's tail; the horse's rump} crown > {Head; top of the head}
304.16
But she againe him in the shield did smite
2 With so fierce furie and great puissaunce,
That through his threesquare scuchin percing quite,
4 And through his mayled hauberque, by mischaunce
The wicked steele through his left side did glaunce;
6 Him so transfixed she before her bore
Beyond his croupe, the length of all her launce,
8 Till sadly soucing on the sandie shore,
He tombled on an heape, and wallowd in his gore.
1 But she again him in the shield did smite