The weapon charge glitch is the single most important thing for a Secret of Mana speedrunner. There's two types of the glitch, explained below.
CPU Weapon Charge GlitchEdit
This one is the one done with one controller. It is done by getting a weapon to level two or higher. Set the weapon to level one in the ACT menu on a computer and let it charge up to 1. Then go to the ACT menu and set the charge to 2. This automatically puts the charge to 2. Then set the charge back to 1. This glitches the game out and lets you charge up the power of your weapon to a maximum of 999 dmg. Don't leave it going too long though, or the damage starts to go back down again and eventually resets.
Two Controller Weapon Charge GlitchEdit
This is the much more efficient way done with two controllers. This method allows the runner to control the attack instead of relying on the A.I. First you get a weapon to level 1 and another weapon to level 2. You charge the 2nd weapon to level 2 and then switch it with the level 1 weapon using a second character. This glitches similarly to the CPU glitch, but you can control the timing, damage, and type of charge attack by choosing the right frames to launch your attack.