While the buff to shield oath helps immensely with the aggro situation, if the DPS in question outgear you, you will have a hard time regardless. Also, your weapon is ilevel 75 which has less weapon damage and strength. They both affect how much damage you deal and how much aggro you gain. All DPS but monks have an aggro dump/slow skill that unskilled people tend to ignore. Also, ask your DPS to focus on one target instead of going balls to the wall on different ones.