A friend of mine made an interesting discovery - unlike Dark Knights and Paladins, Heroes have a weapon multiplier of 1.44 for a 2h sword and 1.3 for 1h sword.
Apparently, this isn't from skills, since it was tested with and without SP.
For Heroes - we can see it is 1.44 for 2h and 1.3 for 1h.
For Paladins - we can see it is 1.34 for 2h and 1.2 for 1h - this is what's more weird to me.
For Dark Knights - we can see it is 1.34 for 2h and 1.2 for 1h.