Should I use a heavier weapon?

Billy Grandy already wrote a thorough, fantastic article on this subject. The short version - heavier weapons don't do a good job of building strength, can cause you to overcompensate in ways that hurt your technique and form, and that you're actually probably better off using a lighter weapon, so that way you can train longer.

Read his article here: https://thehemaists.com/2017/05/07/should-you-be-training-with-an-extra-heavy-sword/