168 That thou hast sought to make us break our vows,
169 Which we durst never yet, and with strain'd pride
170 To come between our sentence and our power,
171 Which nor our nature nor our place can bear,
172 Our potency made good, take thy reward.The core of whole passage is contained in the following words: "That thou hast sought to make us break our vows . . . and . . . To come between our sentence and our power . . . . . . take thy reward." My paraphrase of the above is: "Because you have tried to make me break my vows and tried to interfere with my right to pass judgment [on Cordelia], you must take the consequences ["reward"].
The "reward" of Kent's sturdy wisdom is exile. He has five days to leave the kingdom. If he's not gone, he dies.