Cowardice?

[The Dread Pirate Roberts]

Ok, so what was up with the sons of Feanor (btw, how do we do the dots/accents/etc. here?) not once obeying their father's last words:

Then his sons raised up their father and bore him back towards Mithrim. But as they drew near to Eithel Sirion and were upon the upward path to the pass over the mountains, Fëanor bade them halt; for his wounds were mortal, and he knew that his hour was come. And looking out from the slopes of Ered Wethrin with his last sight he beheld far off the peaks of Thangorodrim, mightiest of the towers of Middle-earth, and knew with the foreknowledge of death that no power of the Noldor would ever overthrow them; but he cursed the name of Morgoth thrice, and laid it upon his sons to hold to their oath, and to avenge their father.

Cowardice?

A man and an elf-maiden accomplished a part of the deed not one of them ever once dared try, even though they swore an oath to relentlessly do so.