By past event weapons you mean Vlad lance. Your orichalcon exchange options for fire are the exchange-exclusive gun (it is assault (L)/defender(M), but it maxes out at 1800 atk) and past raid event weapons. So that means Crom Cruach hammer (defender only trash), Cthugha bow (defender only trash), Adramelech bow (Rush only trash), and Vlad lance (Assault (M)/Stinger(S)) when the exchange opens up.