Syrio Forel vs Jayna: who would win?

Jayna favored — Slight edge (~55%)

Syrio Forel · Game of Thrones · Base

Tier

10-A, up to 9-B

Attack Potency

Athlete Level, up to Wall Level+

Speed

Peak Human, up to Subsonic

Durability

Athlete Level

Jayna · DC · Base

Tier

9-C, up to 5-A

Attack Potency

Street Level, up to Large Planet Level

Speed

Massively Ftl+

Durability

Below Average Human Level, up to Large Planet Level

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