Most 'powerful' lines of Ea....

[Lalaith]

Two of my favorites have already been quoted here - the meeting of Hurin and Morwen by the stone, and Eowyn and the Witch King.
But I would also offer this, which always brings a tear to the eye:

Last of all Hurin stood alone. Then he cast aside his shield, and wielded an axe two-handed; and it is sung that the axe smoked in the black blood of the troll-guard of Gothmog until it withered, and each time that he slewed Hurin cried:"Aure entuluva!" 'Day shall come again!' Seventy times he uttered that cry; but they took him at last alive, by the command of Morgoth..