cicero imagines the state of rome itself.....

[john abshire]

M. Tulli Cicero, quid agis? Isti pro multis factis malis poenas dare nunc debent; eos enim ad mortem ducere debes, quod Romam in multa pericula traxerunt. Saepe Romani in hac civitate etiam cives morte multaverunt. Sed non debes cogitare hos malos esse cives, nam numquam in hac urbe proditores patriae iura civium tenuerunt; hi iura sua amiserunt. Populus Romanus tibi magnas gratias aget, M. Tulli, si istos cum virtute nunc multabis.

M. Tulli Cicero, what are you doing? Those men ought to give (pay) penalties for many bad deeds; for you ought to put (lead) them to death, because they dragged Rome into many dangers. Often Romans in this state even punished citizens with death. But you ought not think these bad men to be citizens; for never in this city did the traitors of the homeland uphold the laws of the citizens; these men gave up their rights. The Roman people will give great thanks to you, M. Tulli, if you will now punish those men with courage.

--the translation?
--cum virtute -- I had the question -- how do you know if the "with courage" goes with the punishing, or the men to be punished, besides context?; but i think I answered it myself; that is, Cum virtute is an "ablative of manner". [a noun, often abstract, that answers the question 'in what manner is the action performed'. "with courage" in this case.]

edits
omitted clause in blue

 

[CORNELIVS XXXIV]

The "ablative of manner" makes sense in this case – given this meaning, you could even translate cum virtute as "courageously".
Because cum virtute essentially modifies the action of punishing, this adverbial translation is actually quite logical (although not literal).

 

[MIB]

I think you made enim to be etiam.
the English drug is sometimes misused for dragged.
you skipped a clause between cives and hi

 

[cinefactus]

The more natural English for ad mortem ducere is to put them to death.