If your main weapon does have floor potency on it, you will be able to reach 100% floor potency without dedicating an extra weapon to it. This allows to take advantage of significantly higher base ATK that your future, harder to obtain main weapon might have.

Whether or not a new weapon is needed, it is recommended to begin by building new armor. Prioritize armors with high PP gain, decent defense, and damage resistance values, we we can not take advantage of armor potency or preset skills. The Behlgren armor is a suitable option.