Honestly? Magnums. I mean yes they're a staple of the modern shooter but they're so often betrayed so poorly. Probably the only magnum I can remember having any real impact is Half-Life 2's. Barely any game since, not even the gun-porn that is the Modern Warfare series, has had a magnum that truly feels real in my virtual hands. I was really hoping Red Dead Redemption would get the whole Clint Eastwood thing going but the pistols in that game were lacking any real feedback, too.
Also, lightsabers. Again, they're in every Star Wars game ever made if I recall correctly (even the space sims had at least one lightsaber in there at one point), but why do they always feel like big glowing space-batons? They chop Darth Maul in half in Phantom Menace and that was a PG-rated sugar puff of a film; why can't I saw through stormtroopers like butter in The Force Unleashed? Ridiculous.