Last November, a man with a handgun executed four Lakewood, Wash., police officers in a coffee shop. Nearly a month later, a man with a handgun and rifle ambushed two Pierce County sheriffs, killing one of them. Proponents of a state law to ban certain “military style” semiautomatic weapons invoked those shootings, but the weapons used would remain legal. The legislation is named for Aaron Sullivan, a teenager who was slain by another teen using a semiautomatic weapon. But as the recent assaults against officers show, all kinds of weapons are lethal and it doesn’t make sense to target some of them with arbitrary guidelines. Under the bill, semiautomatic weapons that hold more than 10 rounds of ammunition would be banned. Those holding fewer would not be. Those with pistol grips or other accessories would be banned, but those add-ons don’t make the weapons more deadly.