How heavy is Whitebeard’s bisento?

No guidebook, SBS or Vivre Card gives Murakumogiri a weight or a length. What is official: Whitebeard (Edward Newgate) is 666 cm (21 ft 10 in) tall, per his Vivre Card entry. Oda named the weapon in the SBS of volume 93 and placed it among the 12 Supreme Grade Blades, the best blades in the world. The Road to Laugh Tale guide calls it a naginata. The rest is our reading of the art: Whitebeard usually holds it upright with the blade above his head, so we took the whole weapon as about 8 m, a little longer than he is tall.

The arithmetic, with round assumptions. Blade: 2 m long, 35 cm wide on average and 3 cm thick on average, so 2 × 0.35 × 0.03 = 0.021 m³ of steel. At 7,850 kg/m³ that is about 165 kg. Shaft: 6 m long and 16 cm across, a volume of about 0.12 m³. In hardwood at 750 kg/m³ that is about 90 kg. The brass collar between blade and shaft and the ball-shaped pommel add roughly 45 kg. Total: about 300 kg.

The shaft material changes everything. Its red and yellow stripes do not say what it is made of. If the same 6 m pole were solid steel it alone would weigh about 950 kg, and the whole weapon around 1,160 kg.

A real naginata is a curved blade of 30 to 60 cm on a wooden shaft, about 1.5 to 2.5 m long overall and usually 1 to 3.5 kg. An Edo-period example sold by the dealer IMA is 8 ft (2.4 m) long, with an 80 in pole. Murakumogiri has the wide, strongly curved tomoe-gata blade shape, which widens toward the tip.

Whitebeard is about 3.9 times as tall as a 1.70 m person. Scale a weapon up by 3.9 in length, width and thickness and its weight grows by 3.9 × 3.9 × 3.9, about 60 times. A heavy 3.5 kg naginata would then weigh about 210 kg. Our 300 kg is higher because his blade is drawn much broader than a real naginata blade.

The heaviest real polearms of this kind were Chinese guandao made for Qing dynasty officer exams, where candidates had to swing weapons of 48, 60 or 72 kg. The heaviest one known, in a museum at Shanhaiguan, weighs 83 kg. Our Murakumogiri is about 3.6 times that.

Whitebeard carries it for more than four decades: chapter 1155 shows him with it on his back 48 years before the present story. At Marineford he swings it one-handed to block a full two-handed strike from the giant Vice Admiral John Giant (chapter 564), and he wraps it in his quake power to knock down dozens of Marines at once (chapter 566).

It does not melt when one of Akainu’s magma fists lands on it (chapter 554). After Whitebeard dies standing, it becomes his grave marker in the New World, with his coat and flag hanging from it. The chapter 668 cover, two years later, shows it still undamaged.