Currently, everyone's battle level is 1. You have to train to increase your battle level. The elf and dwarf can do this at any standard battle training camp. For the other two, it's different, but we'll get to that later. Throg can use any magic items the barbarian can, which would include almost any sword, but as he gains levels, the influence of chaos will restrict this. Hopefully, he'll gain powerful Chaos Artefacts to balance the restrictions. Since this magic sword is of a variety that has no restrictions, anyone in the party except Kelgar (hammers only) can wield it.