[Give him a moment to take a nice, deep, calming breath, so he his tone for Webby is calm, and shows none of his rage. The rage was still there, but not for her.]

It's more than a matter of skill, it's a matter of safety. Here-

[And she's getting lifted up properly so he can point out everything this merchant has done wrong as a learning experience for a child. That way this swill will at least serve some purpose.]

Do you remember what I taught you about cutting your herbs evenly? Otherwise you can't get a proper measurement for your potion, right? Well take a look at his- the edges are frayed, some of them are even half crushed, putting that in a potions could very well alter how it works.