Sea Beast Weapon vs Fenris Wolf: who would win?

Fenris Wolf favored — Slight edge (~55%)

Sea Beast Weapon · One Piece · Base

Tier

5-C

Attack Potency

Moon Level

Speed

Subsonic, up to Speed Of Light

Durability

Moon Level

Fenris Wolf · Percy Jackson · Full Power

Tier

5-C, up to 5-B

Attack Potency

Moon Level, up to Planet Level

Speed

Massively Hypersonic+

Durability

Moon Level, up to Planet Level

A heuristic estimate from normalized VS Battles Wiki stats: tier, attack potency, speed and durability.