I apologize if I wasn't clear in the first post - I meant my own 3d models and not Bethesda's. I made a series of historically accurate weapons. I just prefer them to fantasy weapons. My own favorite is a schiavona, a late 15th century basket hilt sword. I also used a Main Gauche instead of a shield. If dual wielding sword/dagger is now possible that combination will work out even better.
That sounds nice - I might even have your models, if they were posted. I like that sort of stuff and have a few mods of such weapons.
I would sort of doubt that anyone will even bother to do a converter for old nif to new nif. It would probably be possible, and if it's simple I suppose someone might put one together, but I would think the first thing that's going to be done is a converter for a standard 3d modeling file format to the new nif, so the conversion process is going to be to convert your old nifs back to the original (or just start with the originals, if you still have them), tweak them if necessary, then convert them to the new nif format.
That tweaking part could be an issue too. If Beth made fairly extensive changes, then you might even have to make fairly extensive changes to the originals just to make it possible to convert them to the new format, whenever such a converter becomes available.