Generally, weapons are not supposed to work this way so game doesn't expect such items even if they might work. Weapons should have their own animations (noone worked on that yet) and basically you should have an unique attacks for these swords.
It should be possible in the future.
Oh wow, cool items! Don't forget about Light and Darkness too
They're cool items! But you've asked if we should make similar items a while back and we've decided that it was too early.
This is really error-proned because lets say that a player has already leaned Fire 1 magic spell, then got the sword and equipped it... When unequipped, Fire 1 should be gone as well, not because it's a bug but simply because we've agreed that weapons should not work this way.
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I should either write the code that would allow adding affinities and animated attack to weapons OR this should be a separate magical skill (doesn't require any code from me, just modding).