@AbyssalMonkey
Oh come on, he even say it in this chapter, it's an iron sword, it's light... I'm not talking about some monster sword like the one from berserk, i'm talking about normal swords in manga, that somehow weight 10kg.
If the author wants to make an heavy sword, he can do it, but he can't call it an iron sword or a normal sword or whatever, because it breaks the willing suspension of disbelief.
And no, swords were used to cut and slice, they had to evolve to do more piercing, because of the armors that evolved too.