Bruce is a pet acquired by dealing melee damage to monsters while using the Stab attack style.

This page is up to date (v1.3.1).
Bruce
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Pet ID: melvorD:Bruce
Source:
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Attack
Drop Chance: See: Acquiring Pets
Effect: +3 Hidden Attack Level
Part of 100% Completion: Yes

There is no best weapon to use in order to acquire Bruce - increasing/decreasing attack speed or using weapons with special attacks that perform consecutive attacks does not change the chance to unlock Bruce over time.