As the sword had been intentionally left for Arthas to find, and the elemental forces probably cared little for what happened to Lordaeron, the Guardian's motives are unknown. The Guardian, like all other revenants, has some sort of resistance to the Lich King's control over all undead, most likely explaining why he tried to warn Arthas instead of encourage him. Possibly, the Guardian saw the future Arthas would bring as the Lich King and tried to prevent it.
His true intentions were revealed in Arthas: Rise of the Lich King. In the book, The Guardian is just called "the leader [of the group of revenants], the one assigned to guard Frostmourne" and "the strange protector", and the other revenants "the other elemental guardians of the sword" (all by Arthas). Little information is given beyond that and the description of the battle. The only other hints to his motivations are the inscription on the dais being written in Kalimag, and the green ore in the walls of Frostmourne Cavern (speculated to be Saronite, hinting at a connection to Yogg-Saron) being referenced as "softly glowing turquoise crystals and veins of ore".
- The Guardian: Turn back, mortals. Death and darkness are all that await you in this forsaken vault.
- Arthas: I doubt there is anything down here more terrifying than what we've faced already.
- The Guardian: Believe what you will, boy. You shall not pass.
- The Guardian: Turn away... before it's... too late.
- Arthas: Still trying to protect the sword, are you?
- The Guardian: No... trying to protect you... from it.
- ^ "The Scourge of Lordaeron: Frostmourne", Warcraft III: Reign of Chaos. Blizzard Entertainment.
- ^ http://www.blizzplanet.com/blog/comments/chris_metzen_micky_neilson_pocket_star_books_lore_qa_video_interview/ 'Medievaldragon: What were the Revenants' motives to care for Arthas' fate? Will it be explained in World of Warcraft: Arthas, Rise of the Lich King? Metzen: It's in the book.
- ^ Arthas: Rise of the Lich King, pages 178-181
- ^ Arthas: Rise of the Lich King, page 182, Muradin: "Aye, I thought I recognized this. It's written in Kalimag-the elemental language."
- ^ Arthas: Rise of the Lich King, page 178