Can't make a +1 Striking Weapon

I’m unable to add a +1 Striking weapon (in my case, a longsword) to my character. I’m assuming that I’m supposed to be able to edit it under My Formulas maybe? But that doesn’t seem to pop up anything on my fighter, making me think that might be for alchemists. I see and have added the +1 Striking Magic Weapon, the Weapon Potency +1 rune, and the Striking rune. I’ve equipped them all as well, but neither the +1 nor the Striking are being reflected in the calculations on the actions page.