King Elessar suggested that you recruit the Lady Nauriel for the mission to Umbar.
'Every day that passes brings my son further into danger, ${PLAYER}. There must be no more delay.
'I will join the crew of the Wave-hunter so I may ask the Kindred of the Coins to return Thorongil, but I will ask only once. If they refuse I will bloody my sword and dent my shield on their carcasses! They have remained unused for too long, anyway. My husband Carandolion always speaks of the need for patience, and for thinking things through, but see where that has gotten us! Our son stolen away by enemies of Gondor! Well, they have made an enemy of Nauriel, and she does not forgive as readily as Gondor. Recruit the crew you think we will need for the voyage, ${PLAYER}, but remember the need I have for haste.
'Will you retrieve my sword and shield from the armoury on the lower level? I have had the sword sharpened and the shield reinforced since the Corsairs raided Tûm Rost, and they should now be ready for me.'
Nauriel's sword and shield have been made ready for the voyage, and can be found on the lowest level of Ost Arndír.
Nauriel's husband Carandolion is on the lowest level of Ost Arndír.
Nauriel is in the main hall, on the upper level of Ost Arndír.