Hi lil' bro,
With your current build you could play a little with Berserk Pitcher in order to keep the OA, and use the Jaguar Hat for the STR buff, and the Diablos Ring[Osiris] as swap for AGI Lv 5 as mentioned above
Calc with OA in main hand
Next could be to either replace as mentioned above the QS for an Incantation, or just put the OA as second hand and go for a +7-10 Mes[DIncInc] to increase your damage.
Then maybe later once you have your Evangelist you will be able to think about getting the vamp MG ^^