At the end of the story about this labour, there is:
Auxilium enim Hydrae tulit cancer ingens, qui, dum Hercules capita abscidit, crura eius mordebat. Postquam monstrum tali modô interfecit, sagittas suas sanguine eius imbuit, itaque mortiferas reddidit.
A huge crab lent assistance to the Hydra, which, while Hercules hewed off her heads, was biting his legs. After he has killed the monster in this fashion, he soaked his arrows in the Hydra’s blood, and “returned/gave back” the deadly arrows.
I can’t get the correct meaning of reddo at the end. I assume he shot the crab, but I can’t get that from the Latin. Can someone help?
As “reddidit” can also mean “paid back” could this also mean “he paid back the death-dealing thing” (the poison on the arrows in this case). I think he might be using “pay back” in the dual sense that we do - meaning pay back a loan but also pay back an injury. So our attention is being drawn to the irony that the same poison from the Hydra was used to kill the crab.
I think what we encounter here is the special transitive function of the verb ‘reddere’ in the sense of ‘render, make.’ In this case, that would make the sentence as following:
‘he soaked his arrows in the hydra’s blood and thus made them deadly’
Ahhh thank you all. I shall have to read up on this factitive. It’s new to me.
footnote: I found (in a different dictionary) that with adjectives, reddo can mean to make, hence ‘itaque mortiferas reddidit’ becomes ‘and so, he made [the arrows] deadly’.