Promethean Watcher vs Wannai Kinuho: who would win?

Promethean Watcher favored — Slight edge (~55%)

Promethean Watcher · Halo · Base

Tier

9-B

Attack Potency

Wall Level

Speed

Unknown

Durability

Street Level, up to Multi-City Block Level

Wannai Kinuho · Toaru Majutsu no Index · Base

Tier

9-B

Attack Potency

Wall Level

Speed

Athletic Human

Durability

Human Level, up to Wall Level

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