This tutorial is for making weapons that prohibit the use of a shield in shield-using characters as long as the weapon is equipped. This will make it seem like the weapon is a two-handed weapon, simply to add a bit more strategizing to the art of choosing a weapon. First, of course, you will need the weapon you want to make 2-handed to be available in the database. Make a common event, and one conditional branch inside of it for every character that will be able to wield the weapon. For each conditional branch, go to the second page of the condition choices, and select the appropriate character. Make it so that the conditional branch will activate the conditionalized (is that a word?) event command when the character is equipped with the weapon. Then make a 'Change Equipped Items' event command inside of the conditionalized section. Select the character that it's for, and go to the 'Shield' section. Use the default (none), and then repeat for the other characters that can use the weapon. Make an event on any map and put the appropriate common event into activation there. Choose 'Parallel Process' for the trigger. Also, check the check box for 'Phasing' under options, just in case. Finally, copy the event and paste it to every other map in the game.
Note: It's not perfect, as it doesn't prohibit the re-equipping of the shield, but as soon as the player exits the pause menu if they try to re-equip it, the event will remove the shield again.
Note: It's not perfect, as it doesn't prohibit the re-equipping of the shield, but as soon as the player exits the pause menu if they try to re-equip it, the event will remove the shield again.