[burrahobbit]

An Elf that had been to Valinor, such as Glorfindel, exists on two planes just as the Nazgul. I think that he would hurt the nazgul on both planes if he hurt it at all. A regular elf like Legolas or any man would just be on one plane, and so would need a special weapon to to lasting damage. Merry stabbed the Witch-king with his barrow blade, which functioned as a sort of anti-morgul blade to bring WK out of the world of the unseen (as opposed to the morgul blade bringing you into the world of the unseen), which allowed Eowyn to kill him fully. Glorfindel wouldnt need WK to be pulled anywhere, they both exist in the same places already.