The Faithful Squire is a quest available in The Elder Scrolls IV: Knights of the Nine. After collecting all the other Crusader relics: the Boots, Gauntlets, Helm, Cuirass, Shield and the Mace, return to the Priory of the Nine.
Talk to the knights about the remaining relics, the Greaves and the Sword. After entering the Priory, the Squire of Sir Roderic is there. He tells a story of his master and how he visited all of the Wayshrines and received a vision, apparently a disturbing vision. After the vision his master kept mumbling about some old family and asked around for them. Finally they went to Underpall Cave searching for the Greaves and the Sword of the Crusader. Once there, an unholy wraith attacked and killed Sir Roderic.
He then asks if he can become a Knight, if his request is accepted, he will get into the appropriate gear and join the quest to kill the wraith that murdered Sir Roderic and claim the Sword of the Crusader.
Lathon, the young squire of Sir Roderic, arrived at the Priory with a tragic tale. It seems that his master perished while attempting to defeat the dreadful undead guardian of the Sword of the Crusader. Lathon was able to escape with the Greaves of the Crusader, which he surrendered to me. I have made him a Knight, and asked him to accompany me to Underpall Cave where Sir Roderic fell. We will avenge his former master and reclaim the Sword of the Crusader for the Nine.