It's just Etzel trying to save his old obession that Tuon and Rand will ally very early and Rand will send the Senchan to save the Tower.
His idea that Rand meant to hand Semirhage down to Tuon has of course not panned out, so now he's conceived this new one, not much better at all IMO, that Tuon would be swayed Rand's side by being given a shiny sword.
Surprising he's not found a way to tie the sword to Slayer and Asmodean's murder, yet 
IMO, my ideas are at least as valid as your idea that Tuon will leave the south with all her troops to invade the Two Rivers, or some such nonsense..

They are at least based on some Prophecies.
Besides, it isn't said that Rand won't yet hand over Semirhage to the Seanchan, if he got his needed informations from her and if the Seanchan finally demand to prosecute Semirhage for what she did to the Imperial Family.
For that matter, we also don't know yet if Rand won't eventually agree to torture Semirhage, if something dire happens, e.g. Bashere's death or Moridin messing with Rand via the link (similarly to Perrin's torture situation in CoT). Jason indicated that there are dark things, especially concerning Rand.
As said, the sword could become an additional gift during the talks with the Seanchan or maybe it's linked to a Seanchan Prophecy.
The theory that it's Guaire Amalasan's sword doesn't seem to have any plot relevance and is therefore quite unlikely, irrespective of the other problems, especially why Rand recognizes it and why the people who gave it to Rand are "completely unaware of what they were holding" (TGS, ch.1), if the Dragon scabbard would point to a False Dragon.
Plot relevance of the sword
- 06/09/2009 04:25:12 PM
1474 Views
Great
- 06/09/2009 08:01:07 PM
964 Views
Re: Great
- 07/09/2009 04:02:53 AM
875 Views
Re: Great
- 07/09/2009 11:53:52 PM
899 Views
Re: Great
- 08/09/2009 10:57:13 PM
1089 Views
I see that differently
- 09/09/2009 02:15:45 AM
880 Views
Re: I see that differently
- 09/09/2009 05:24:55 PM
809 Views
Well...
- 09/09/2009 03:59:27 PM
935 Views
Nice
- 07/09/2009 02:46:36 AM
859 Views
Re: Nice
- 07/09/2009 04:00:53 AM
881 Views
? Yes, I am aware of this
- 07/09/2009 04:24:03 AM
855 Views
Re: ? Yes, I am aware of this
- 07/09/2009 03:36:45 PM
829 Views
I'd favor it being Justice, they probably tell us in the prologue
- 09/09/2009 05:46:37 PM
847 Views
My early theory: High Lord Turak
- 08/09/2009 08:11:24 PM
1368 Views
All good points but a couple of puzzlers
- 09/09/2009 02:06:59 AM
907 Views
see above for part
- 09/09/2009 02:20:19 AM
853 Views
OK, I see what you are getting at, but I'm not sure I buy it
- 09/09/2009 12:14:10 PM
837 Views
Re: OK, I see what you are getting at, but I'm not sure I buy it
- 09/09/2009 02:59:30 PM
857 Views
No, He's giving me way more than I want.
- 09/09/2009 05:27:31 PM
793 Views
Additionally, re: Why the Dragons?
- 09/09/2009 03:08:27 PM
867 Views
Re: My early theory: High Lord Turak
- 09/09/2009 05:29:11 PM
889 Views
