The Nasgareth may look like elves, but instead were created by an entirely different divine being, which admired the elvish looks and traits, but wanted to create his own army instead. One without Love.
The dwarven gods true names can only be known by dwarves. They are referred to by nicknames in the presence of non-dwarves. I.E. Gudurran( Allfather) Baenna ( Hearthmother) Dudrak ( Ore), etc. No torture or magic or direct intent can reveal their true names to non-dwrves.