There's nothing wrong with using DPS weapons for tanking, provided you are defense capped and you don't have survival issues. Murmasa in sunwell was a great weapon of tanks because the nearest tanking weapon wasn't enough.
However, the point is moot. Your expertise is at 10 adn your hit rating is not exactly capped either. Get to 26 expertise, and regardless of what weapon you are using, be it Rimefang, Scourgbourne War Axe, or even THIS or THAT, you should not have threat issues to deal with which are solved by a new weapon.
If you want to get to get geared better, try for the following:
Expetise/stam in helmet
Replace 30 stam in shoulders with hit/stam.
pants, boots, ring should be expertise/stam instead of agi/stam.
Replace 30 stam in belt with expertise stam.
Replace gloves with hit/stam