Complex sentence: There is some debate over the exact circumstances of Talbot's death, but it appears as though his horse was killed by a projectile, its mass pinned him down, and then a Frenchman killed him with an axe.
Split into simpler sentences: There is some debate over the exact circumstances of Talbot's death, but it appears as though his horse was killed by some sort of projectile. Its mass pinned him down, and then a Frenchman killed him with an axe.