Orcrist

[deal_with_it]

I never heard it was broken, but I may be wrong I just wasn't sure (if it was whole) whether or not it was buried with THorin or not. If it was I could see not digging it up, but in a life threatening situation I might take that chance.

http://www.glyphweb.com/arda/default.asp

"The sword of Thorin Oakenshield, discovered by him in a troll-hoard on his journey to Erebor, and buried with him after his death in the Battle of Five Armies.

Notes
1 Exactly what happened to Orcrist at Thorin's funeral isn't completely clear. The Hobbit tells us that the sword was placed by Thranduil 'upon his tomb', and that it 'gleamed ever in the dark if foes approached' (The Hobbit 18, The Return Journey). These quotes seem to suggest that Orcrist wasn't actually buried with Thorin, but instead just laid on his tomb.

In The Lord of the Rings, there's a suggestion that this may have changed. We are told there that Orcrist '...lay now upon the breast of Thorin...' (The Fellowship of the Ring II 3, The Ring Goes South). This seems to suggest that the sword was actually placed within Thorin's tomb, and not just placed on it, though this text is admittedly ambiguous."

[Eonwe]

Hmm, I seem have a propensity for making things up...

[Elu Ancalime]

These quotes seem to suggest that Orcrist wasn't actually buried with Thorin, but instead just laid on his tomb.

In all seriousness (well...a little humor) what if it fell off?

Its another one of those slip of Tolkiens from transferring information from series to series. My guess is that Tolkien meant it to be placed on his tomb, then rather on his chest. Like was aforestated. He would have meant for whatever was written in The Hobbit to stand, since for one he wrote it first. Perhaps!
________
Chrysler lebaron

[Rumil]

I guess one benefit of leaving orcrist on top of Thorin's tomb was that the Dwarves could tell if orcs were close to the Lonely Mountain by the gleam from the sword (as for Sting), and so avoid being surprised.

I'd imagine some sort of very solemn duty guard of dwarven soldiers guarding the tomb of Thorin and able to raise the alarm if Orcrist lit up, must have been exceptionally boring!

[The Sixth Wizard]

I'm sure it's just a thing that they do with their kings, I mean Boromir wasn't that important and the Horn of Gondor went with him to the sea.

[lathspell]

The actual quote from the Hobbit runs thus:

Actually is was some days before Bilbo really set out. They buried Thorin deep beneath the mountain, and Bard laid the Arkenstone upon his breast.
"There let it lie till the mountain falls!" he said. "May it bring good fortune to all his folk that dwell hereafter!"
Upon his tomb the elvenking then laid Orcrist, the elvish sword that had been taken from Thorin in captivity. It is said in songs that it gleamed ever in the dark if foes approached and the fortress of the dwarves could not be taken by surprise.

So it seems clear that the Arkenstone was lain upon his breast by Bard. Thranduil did indeed lay Orcrist on his tomb. Another point is the rumour about the songs in which it was said that Orcrist gleamed if foes approached the mountain. I mean, why sing anything like it if you can't see the blade anyway? It is, I think, a heartening thought after all the dealings with Smaug that you wouldn't have to worry anymore about such things, because if another Dragon came from the north the sword would gleam. Wether the story is true... who knows?

Now, back to the original question of this thread. Why didn't Dain fight with Orcrist?
If I remember correctly, in mythology dwarves generally are very reluctant to use one another's tools. There most beloved tools for crafting or weapons in battle were therefore not lightly used by another dwarf. I do not know if Tolkien used this dwarven characteristic in his books, but it might be. Then Dain wouldn't have taken Orcrist from Thorin's tomb, unless he had no other choice.
Another reason could be that what Orcrist was for Thorin, Dain's axe was for him. It is said in UT that Dain wielded his axe with great power. Maybe he had a greater power when fighting with his axe then with Thorin's sword. It is like Aragorn and Anduril. Anyone can carry Anduril and stab an orc with it, but Aragorn is the only one who van actually wield the power of the sword.

greetings,
lathspell