I know, the topic is quite old, but it os one of the first appearing, when I searched for weapons and skills^^
as @Prometheus wrote already, different weapons are needed for different spells/abilities. I guess, that even some of the 6 Quests to discover new spells might be to fight with a specific weapon. Is this planned? I think it would at least fit in the style of quests, if there are also some spells where you need to die to discover them^^
But back to the topic: As we know, that some weapons and Armor will be only available at some planets because of the materials, and if they are linked to abilities, is it then possible for e.g. Beastmen to learn an demonic ability by using a weapon of tartaros, if they travel there? Or is it not possible to obtain a weapon which is not belonging to the own Race?
There are so many options