The warrior was Baldor, first son of Brego the Second King of the Rohirrim. During the feast to celebrate the completion of Meduseld in 2569 TA, Baldor vowed that he would tread 'the Paths of the Dead'; this he did, but failed to complete.

I have often wondered if the cronies of Aldor, his younger brother, got Baldor in his cups and then by insinuating that it would be cowardly not to tread the 'Paths'. This would have been to get the throne for Aldor when Brego finally died, which he did a year later, of a broken heart over the loss of Baldor. This conspiracy theory is probably hogwash, and the truth is probably more that Baldor was Boromir-like in that he also had to be the one to do it.

As for the treasure, I think that is unknown. When Aragorn was gazing at Baldor's remains, before the fast closed stony door he said:The above was found in the ROTK, Book V, near the end of Chapter 2 entitled 'The Passing of the Grey Company', and also bits were gleaned from Appendix A of ROTK.

quite soon i think as in the tales would have passes round about a certain man now a king long gone passed that path and lived to tell about and cleanse the countries surrounding

*sniff* Nice thought yeah...

Nope, a Third Age conspiracy, you are welcome!

oh I agree, Lucien...I'm really interested to see how they're going to do it...keep your fingers crossed that it won't get cut...