Stabbing in the eye works for mortal creatures. Not so much for zombies, vampires, demons, elementals and similar beings that don't have vulnerable parts, don't have functional internal anatomy, don't bleed or feel shock so minor wounds won't kill them and so on.
A leviathan, that is both a supernatural entity and the size of a battleship, is not going to even be annoyed at the efforts of a speck armed with a sword.
And as I've already said, in what way does making large weapons a catch portray this? It doesn't. The small weapons are still just as likely to cause damage as they ever where, and all your doing is taking a class of weapons that already had rules to cover the massive damage they do, and doubling their effectiveness for no logical reason.
The zombie argument is just plain wrong as whether or not the zombie needs its brain to live, it still needs its eyes to see. If you blow its head off, whether it remains animated or not, its taken out. Thats why Zombies have toughness and not immunity, they can still be taken out by anything.
The Leviathan example is also irrelevant, as it would have immunity. If you're flat out immune to all lesser damage then setting the catch as "Antitank weapons" is fine.
As an aside, the effectiveness of a weapon for satisfying a catch, should never be based on its game stats. saying, "weapon rating 6+" doesn't make any sense, as a warden sword and some items of power are weapon 6 and still aren't big enough to overcome the armor in those examples.
