1)Phogoth is actually the easiest to solo. 2) Why would you attempt to use any kinetic weapons w/ a burn? 3)Arc burn weapons are extremely rare? Only the heavies are rare, where are you getting your weapons? you can buy a vanguard arc sniper, and Eris gives u a fusion rifle for completing her quests. play the game, and you'll get them. 4) There are more arc primaries than any other damage type. 5 to be exact. 5) It's not extreme luck, just experience