—, If you are planning to have hundreds of weapons you should definitely re-think your approach..
I would make a "database" of all available weapons:
You can create this table in Excel, save as text file (.CSV) and import to Construct 2.
Use CSV plugin to read data from this file, it's pretty simple.
Another option - XML. But personally I prefer CSV.
When you have your weapons database, you can select several weapons from it (by current level, shop type) and put them into the shop. Create sprites, set animation, arrange them on the shelves, etc. Set instance variable on each sprite to weapon code.
So for example you'll have instances with codes "ShortSword_2", "LongSword_2", "LongBow_2".
When player clicks the long sword sprite, you can retrieve all other information from the CSV by code "LongSword_2". Deduct its price from player's money, update weapon in player's hand, update damage values etc.
Edit: I just noticed that you are planning to sell armor and other items. You can make similar databases for them.
Or maybe combine everything in one, but it may become too complex.
Also, I suggest you learn how to use loops and functions, it will make your life much easier.