Complex sentence: One-Eye has Speckles in a near-fatal grip but seeing Blue Eyes suffer, Speckles has a flashback of his mother's death at the hands of One-Eye and recovers the strength to beat him.
Split into simpler sentences: One-Eye has Speckles in a near-fatal grip. But seeing Blue Eyes suffer, Speckles has a flashback of his mother's death at the hands of One-Eye and recovers the strength to beat him.