Bleach's combat system is centered around zanpakuto, or soul-cutting swords. In the first two story arcs, zanpakuto were exclusive to Soul Reapers, who could release these swords' shikai and bankai to great effect. Then, Bleach's combat system was expanded to include the Arrancars and their own zanpakuto, or sword-shaped containers for their original Hollow powers.
Source:https://www.cbr.com/bleach-deadliest-arrancar-zanpakuto-ranked/