Well, it is easy.
Firstly honestly i don't got your problem, but probably you're wanting like this:
var link = 1
sprite1.texture = load ("res: // Assets / Magic RPG / Sword / Effects /"sprite" + str(link) + ".png")
But you should change name of your sprites, example:
1.sprite1.png
2.sprite2.png
etc etc..
i hope this will help you.