Kamen Rider Killbus vs Arata Sanada: who would win?

Kamen Rider Killbus favored — Slight edge (~55%)

Kamen Rider Killbus · Kamen Rider · Base

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Massively Ftl+

Durability

Complex Multiverse Level

Arata Sanada · Digimon · Eater Arata

Tier

1-C

Attack Potency

Complex Multiverse Level

Speed

Relativistic, up to Immeasurable

Durability

Complex Multiverse Level

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