One of those things in fantasy (games and otherwise) that has always struck me is that there are special, often-legendary weapons that are particularly effective against certain specific kinds of creatures, like "this sword was forged with special magics and is especially effective against fire dragons." In the general majority of fantasy games, the characters are expected to be the types of people who pick up that sword and slay the fire dragons with it, and not being able to make such a thing themselves means more quests, so the rules for making such a weapon (magically, anyway; "special materials" still require quests to find and so are often put in) are omitted. I wouldn't say that's a bad thing; in combat-centered games, making such a weapon yourself without having to quest for the material to make it would do nothing for the game but let players skip quests. However, Ars Magica is not focused in that particular direction; it's not about combat, or even necessarily quests to acquire materials, and being the "fabled crafter of the Awesomely Named Blade of Slaying Fire Dragons" is a much more tenable choice than in most adventuring-based fantasy games.
However, in the books I own (core rulebook, Covenants, HoH:TL, HoH:S, RoP:I, and RoP:D, though I admit I haven't given the HoH books a deep read) I've seen no way to make a weapon or item that works particularly effectively against specific species of creature. This sounds like something somebody with Faerie-based Supernatural Abilities (is there a name for them? We've got Wizards, Infernalists, and Clerics or whatever you feel like calling Divine Ability-users) would have a knack for; given all the legends associated with weapons (well, items and materials in general, and sometimes food, but you get the point) that are especially potent against specific creatures, and the stories that would obviously be born from somebody searching for and wielding such a weapon, creatures of story like the Fae would probably have a monopoly on designing such a thing. Of course, I could be wrong.
So, are there any ways to make weapons that work especially well against a certain kind of creature, more specifically than just by Realm or Form association? As far as I've been able to tell, the closest thing would be an Intellego effect also enchanted into the item to tell when the weapon is being used against a certain type of creature so it can activate other effects that are just generally powerful, but that feels really cheap, not to mention there would be no real reason for a wizard to intentionally enchant a weapon like that. That's part of the reason I'm looking at other things than Hermetic traditions, but, well... You probably noticed I don't own very many of the books, so I don't know what non-Hermetic source to draw from.
Do one of the books I own have what I'm looking for? And if not, what should the next book on my shopping list be? Does the ability to make such a weapon even exist? (Am I just being derpy and missing something right in the core rulebook?)