mercy > act of mercy enlarge > set free thrall > captive
4 Whose freedom shall you turn to greatest scathe.
scathe > harm, damage
5 Natheless now quench your hot emboiling wrath:
Natheless > Nevertheless emboiling > {Boiling with rage; SUS}
6 Lo, there they be; to you I yield them free!" 7 Thereat he, wondrous glad, out of the path
Thereat > Thereupon he > [Pyrochles]
8 Did lightly leap, where he them bound did see,
lightly > quickly
9 And began to break the bonds of their captivity.