Mihawk Yoru Black Blade Debut

The seed

• The Saijo O Wazamono rank-system — Mihawk’s finest-in-the-world descriptor pre-loads the sword-grading rank-system (12 Saijo O Wazamono, 21 O Wazamono, 50 Ryo Wazamono) that lands in detail at Thriller Bark.
• Black-blade as visual idiom — a sword that is literally black is the visual identifier of a graduated named sword (Mihawk’s Yoru, Roger’s Ace, eventually Zoro’s Shusui/Enma). The black-blade visual idiom installs as the graduation-state of a named sword.
• Zoro’s eventual sword-blackening goal — Wano (and beyond) seeds the possibility that Zoro must eventually blacken Wado (or another sword) via Conqueror’s-haki imbuement, in the way Mihawk’s Yoru is black. The Ch. 51 black-blade debut is the visual-goal-state Zoro spends 1000+ chapters working toward.