It's war, they're the enemy. the fact they have a smaller weapon than you doesn't give them a free pass. It sure as hell wouldn't in the real world.
If you don't like the threat of being ganked, then play on a PvE server. the solution has been the same since day one.
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So PvP servers should be banned? If not where do you set the limit?
Players can only engage in PvP combat with players of the same level - But he has way better gear than me, waaaah!
Players can only engage in PvP combat with players of the same average itemlevel - OMG Blizz, you're making PvP impossible to find, waaaah!
Look, it's simple. If you can't handle the potential risk of getting ganked, then go reroll on a PvE realm. PvP realms are obviously not the right place for you.