In a way, it could make jacks with 3 items more difficult to kill as they'll likely have lace/health/helm (more defense, less offense). But having just learned that clubs, hearts, and diamonds can proc off each other, it makes sense to restrict claws on jack.
I don't think it's necessary to restrict claws from every race with hit-based abilities--in fact, I like the strategy aspect that it introduces. Rapscallion (with an average KDR of 0.52) already has such a low proc rate on blades that buying claws is a virtual necessity. A flame pred with claws often beats a flame pred with health because he has double the chance to set the other on fire (a death sentence for a knife race).
While we're on the topic of item restrictions, may I suggest restricting the helm of excellence from molecule? The high chance to evade and impenetrable shield already make molecules extremely difficult to kill with a race other than shadow hunter, especially if they have health + helm. I don't know the chance for evasion, but for ease of calculation, if it's 33.3%, that makes 150 HP comparable to having 225 HP. You'd have to do an avg of 225 DMG, of which 33.3% or 75 DMG, would be evaded, to actually deal 150 DMG. So with 225 HP, a helm, and shield (impenetrable by all but one race) that lasts several seconds and can be used all too frequently, it's no wonder that molecule has by far the highest average KDR of any race on the server at 1.62 KD (followed by crypt lord at 1.45, spider man at 1.35, and shadow hunter at 1.29. Considering all this, I feel as if a well-placed shot to the head when a molecule is not bubbled up should be lethal, as long as it's not evaded.