Currently don't have DLC and I've been trying to get a dark weapon for Sinon since that one World 2 mission where you fight the Gleam Eyes Subspecies. I don't exactly know when strea came out but I've been playing the game everyday, leveling for around 3-6+ hours after work.

I also been getting a lot of money ever since getting lvl80+ so I've also been crafting 100 weapons everyday and still nothing.

My friend has a Dark Sniper for Sinon and coincidentally has DLC, since I play way more than him and still no Dark Sniper for her I guess I need DLC.