oi, that's a tough one, really tough to get it accurate. the almost the same question was asked here some time back, but there was no set in stone definite answer, as lore is not all that specific from what i understand. i'd point you to the the topic, but its lost by now(it was pruned, i double checked
). unless someone saved a copy of it somewhere, its gone. and i think this would be better answered in Lore forum, as they'd have to give their input as to what's more lore friendly versus something else.
i think(and "i think" applies to all of what follows
), you can safely eliminate any skill set that's all stealth, or all mage or all warrior. Nerevar was a general, so a warrior-mage mix, with emphasis on warrior more, i think. weapons: swords, daggers and blunt weapons i think are more likely choices. armor: either light or medium because i don't think he'd have used heavy armor(though i can't discount the possibility that he was, as a warrior, trained to use heavy too, maybe(would make sense)). i'd say medium, as i am pretty sure Indoril Armor is medium and lore wise, Indoril Armor helmet was based on what Nerevar would have looked like(the Helm at least, not sure about the rest of the armor pieces) and it makes sense that if Nerevar used medium armor then Indoril would be medium to better keep with the lore). on spells: hard to say, for my at least. battle aiding, i'd say, but i can't say which school specifically. everything else, kind of hard to say, will have to be pieced together by looking over lore more.