Recently, I got Hot Toys T2 T-800 and T1 T-800. Both of them are really nice figures.
I was looking into some fire powers for T2 T-800. Most of the people prefer to put the following items to T-800.
1. COO MODEL U.S AMRY M79 GRENADE LAUNCHER NO:X80011
2. COO MODEL U.S. M134 type "rapid-fire machine guns" NO:X80012
3. COO MODEL U.S. Travelers equipment (Black) No:X80014 (A bag for holding the machine gun)
4. For the extra hands in black, many people like to get Joker DX hands.
You can get most of the above items from eBay. They are not too expensive. Hope it helps!
BTW, go to YouTube and search the keyword "HOT TOYS T2 T 800 update". This guy upgraded his T800 pretty well. Tried to include URL for you. However, the site here wouldn't let me.