Turnus is likened to an African lion, who, although pierced by the spears of hunters and seriously wounded, has an undiminished spirit and shakes away these weapons. Carthage, mentioned at the beginning, is meant to make the reader think about Dido, who too we are told in Book 4, suffered a wound (of unrequited love). Carthage re-emerges to spell potential doom for Aeneas and his men. Whether the simile is effective is up to you but justify your opinion either way.