I'm not sure if there are any plugins available that do this. If you go the plugin route, you could use a separate text file to enter in a list of names for weapons and have the plugin create the weapons dynamically. You could use a total of 20 names and randomly generate a prefix or affix to each name. As for the stats those can be randomly generated based on the difficulty range of an area or based on name or whatever seems right for your game. There are many different ways to approach this, including making a separate editor application, to read the RPG Maker database and give you the ability to go past the database max, giving you control over every item. The application way, you would have to use that application to do all database work past the max in the default mv editor. The plugin way seems more accessible and easier because instead of thousands of items, you're creating a few items and randomly generating them based off the originals.
