Warrior, Black Prince, and changing warship classifications

Were Warrior and Black Prince battleships later reclassified as armoured cruisers?

No; they were armoured frigates from an early ironclad era whose design position later overlapped categories that had evolved around them.

The claim that the ships simply moved from battleship to armoured-cruiser status by bureaucratic whim does not fit their service history. Warrior and Black Prince entered service as armoured frigates when that term could describe ships near the top of the naval hierarchy. They occupied an early ironclad center point from which battleship, armoured-cruiser, and protected-cruiser design strands later diverged. The ships did not physically transform when the vocabulary changed, but the surrounding fleet and meaning of each category did. Their reclassification therefore records an evolving naval system rather than a clerk casually redrawing a label.