In the end, he went with the classic trio of sharpness, indestructibility, and lightness, which was tried and tested in the form of Valyrian Steel. Compared to invulnerability enchantment, indestructibility was one step stronger, and it would be much harder to overcome, on top of the fact that the bronze alloy was a far better conductor of magic, making the effects generally stronger. While Valyrian steel could generally be melted down and reforged or reformed, his bronze would require temperatures impossible to reach with the current level of technology in this world. They could potentially reforge it by using blood sacrifices; however, they would have to kill a lot of people to overcome the calibrated ritualistic sacrifice of a set of seven grown soldiers that fuelled the creation of his spellblade, which was also a tall task.