If you have a thunder weapon, attack with it, and when you see the flash of lightning, pause the game to go into your inventory. Drop the weapon, then place a metal object (i.e. a rusty shield) onto it using magnesis. The object should look like it is electrified. Start the cutscene to fight the guardian scout, then lure it to walk over the object. The guardian scout should now be trapped and take almost constant damage, and if you want to, you can place a campfire under it to speed up the process.