It is an unusual way of using old or archaic English words and putting them in an unusual order to create an impression of antiquity inside a story. Archaic - doth means does Rearranging the sentence to put it in its usual order and trimming extra words out. The result is The bold lion holds the lamb. Note: The extended quote is from a sentence in 'The Legend of Sleepy Hollow". And the sentence echoes back to an American reading primer of about 320 years ago. the lion bold, which whilom so magnanimously the lamb did hold. I have no idea what the phrase 'which whilom' means.

It means that the lion represents the predator and the lamb the prey .