This is my version of how to make a Blacksmith that gives you random pieces of equipment after giving him a forge-able material.
This event requires a bit of setup and can get complicated, so I have tried to explain as best as I can.
This event requires: an item to give to the blacksmith, the equipment that the blacksmith 'makes', a variable to use for randomizing the item given by the blacksmith, an event to change the variable, a control switch to stop the variable changing event and an event to represent the blacksmith.
First make the items. Make an item (Iron Ore for example) to be used as materials for the blacksmith. Then make the equipment to be received (Iron Sword, Iron Armor, Iron Shield).
Next create the variable changing event. Set the trigger to parallel process. Set the first event command, Control Variable. Create a variable and name it something like Blacksmith Item. Make sure that Operation is on Set, and the Operand is set to Random. For Random set the numbers between 1 and the number of items the blacksmith can create from the item you give him.
If you want you can set a Wait command. This will cause the event to wait a moment for the variable to change. Set the Loop command at the end to cause the even to loop again. (From my experience you don't need to do this because of the parallel process trigger, but you can if you want).
On this same event create a second page. Under conditions choose a Control Switch. Name it the same as the variable so you know they're related. That's it for this event.
(If you want to have more than one item for the blacksmith you will need one Variable per Item. You will only need one switch,)
Next create the Blacksmith event. First create a Show Choice command for yes or no and an appropriate message like "Create Item?" Under the Yes branch, create a Conditional Branch for whether or not the material Item (the Iron Ore for example) is in your inventory. If yes create a message like "Okay, let's make an item." Then remove the material item from the inventory. Now turn on that Control Switch you made. This will stop the event that changes the variable (this is mainly a way to prevent any unforeseen bugs). Now create Conditional Branches for when the variable is at each number you made it to randomly change to (like 1-3). Under each branch add whatever item or equipment you want to give to the player. Make sure you only give one item per branch. Then create a message telling the player what item they got. Then turn the Control Switch off so the variable can change again.
You will need to set up all of these conditional branches for each item you want to give to the Blacksmith.
If you get confused I am more than happy to help you.