That makes sense. Per the Grantland link above, they're casting Randyll, his mom, sister(I'm guessing) and brother as well. Him having a Valyrian steel sword + being Sam's dad, I can see him being important. Plus didn't they say we were going to see the Reach and Highgarden coming up?

What's the current count on known Valyrian Steel swords? Tarly has Heartsbane, Brienne has Oathkeeper, Tommen has Widow's Wail, Jon has Longclaw. It's hinted that Aegon might have Blackfyre. No mention of Dark Sister, even though Bloodraven did possess it.

I googled and apparently House Corbray, one of the Vale houses, has one, Lady Forlorn.