How do I make an item system like diablo?

I want to be able to drop "Kings Sword of Haste" or "Godly Plate of the Whale"

Prefix and suffix that means different modifiers.

How would you go about and do that? Where do I store all the info?

I am using construct 2 but i hope the answer will be applicable for me as well.

What stage are you at ? Did you already make an inventory system ? If making an inventory with an array I guess you would need 3 columns for the weapons with stat 1, weapon, and stat 2 in different columns. You can display the weapon name by using all 3 columns. Or if the game is more object based you can use 3 instance variables on the weapon object and when equipped then weapon.stat1 and weapon.stat2 mean something.

I don't have an inventory system yet.

The final items would be best as objects with instance variables describing the modifiers and name.

Suppose I would make the prefixes and suffixes also as objects with modifiers and name as instance variables. How do I create a random object from a list of possible outcomes?

You can create the weapon object and set variable 1 to choose(Kings,Godly) and then variable 2 to choose(Haste, the Whale) for example it picks one of the options.