Why HMS Warrior could dominate the fleets of Trafalgar

What was the first single warship that could have defeated both sides at Trafalgar?

Probably HMS Warrior, whose armour, range, and mobility would let her destroy the wooden fleets while surviving damage to unarmoured fittings.

Warrior is chosen as the first single ship likely to defeat both Trafalgar fleets, although her exposed rigging could still be damaged. Her armour would protect the fighting core while range and manoeuvrability let her control the engagement. Warrior offers a clearer margin of superiority than the French Gloire in this counterfactual.