Blessings can be received as a drop from the god commanders at the event area. They give +1 prayer bonus and goes in your ammo slot.
An avernic hilt is a drop from Theatre Of Blood, and it is combined with the dragon defender to make the avernic defender. Better stats, for sure.
A twisted buckler is a drop from Chambers of Xeric (Raids 1). It is a shield that you use for ranging as it gives you a ranged attack stat of 18 and decent defense stats. I wouldn’t say it’s worth getting, in my opinion.
A treasonous ring is a drop from Venenatis; great for its stab attack stat. A tyrannical ring is a drop from Callisto; great for its crush attack stat. A ring of the gods is a drop from Vet’ion; great for its +4 prayer bonus. All of these rings can be imbued with an imbuement scroll to double their stats.
Guardian boots are basically bandos boots combined with a black tourmaline core from the Grotesque Guardians boss. Great boots for tanking, but I’d use primordial boots for their offensive stats.
A heavy ballista is a ranged weapon that players tend to use for PvP. All four of their parts are dropped by demonic/tortured gorillas. The heavy ballista takes javelins as ammo, up to dragon.
Hope my answers helped!