soon > soon; immediately
3 For all too long I burn with envy sore
envy > desire, enthusiasm
4 To hear the warlike feats which Homer spoke 5 Of bold Penthesilea, which made a lake
Penthesilea > (Daughter of Mars and Otrera, the queen of the Amazons. After Hector's death, she came to the aid of the Trojans, but was finally killed by Achilles (or his son Neoptolemus, according to popular legend). She is not, incidentally, described by Homer, but see Aen. 1.490-3, where she leads the Amazons into battle) which > (Referring to Penthesilea or her feats)
6 Of Greekish blood so oft in Trojan plain;
Greekish > Greek
7 But when I read how stout Deborah struck
stout > bold, brave; proud Deborah > (See Judg. 4.4-21; Sisera was actually dispatched by Jael)
8 Proud Sisera, and how Camilla has slain