Did, fairly recently, a wierd bloke run up to him and throw somethig at him, then say somethig about 'funny, that usually kills them' or something, then run off? when that happens, all your weapon slots change to a scmitar for a very short time, then back to normal again. If they didn't change back then you may have a problem and I ould advise you re-load an old save.
If a bloke didn't throw a sword at you recently then you really do have a problem and definitely need to reload!
Hope this helps a bit
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Nicodemus Deathslayer, Paladin of the Order of the Holy Flame