I recently thumbed through some of Jon’s AGoT chapters again and stumbled upon the scene in which he receives Longclaw.
In the show there’s not much explanation given as to why Jeor decides to give Jon the sword; obviously he’s earned it by saving Mormont’s life, there’s an undercurrent of a father-son relationship there, etc., and we understand all that from the dialogue they have in the scene. But in the book there’s this passage:
“The fire melted the silver off the pommel and burnt the crossguard and grip. Well, dry leather and old wood, what could you expect? The blade, now…you’d need a fire a hundred times as hot to harm the blade.” Mormont shoved the scabbard across the rough oak planks. “I had the rest made anew. Take it.”
And then further down the page, after the line about Jorah having “the grace to leave the sword behind”:
“My sister returned it to my keeping, but the very sight of it reminded me of Jorah’s shame, so I put it aside and thought no more of it until we found it in the ashes of my bedchamber. The original pommel was a bear’s head, silver, yet so worn its features were all but indistinguishable. For you, I thought a white wolf more apt.”
Going by the show’s dialogue I had always assumed that Jeor had simply gotten rid of the original pommel and replaced it with a wolf, as a gesture of thanks to Jon. And that always seemed wrong to me; knowing how proud all the rest of the Mormonts are, I was a bit surprised that Jeor would just do away with the bear pommel entirely and replace it with a wolf. Even considering the fact that he’s supposed to have let go of family ties when he took the black - though he doesn’t try very hard at all to be subtle about how much he still loves his son jfc - that seemed like a drastic move to me.
Except that’s not what happened.
What happened was Maege sent the family sword to him, even though he was supposed to have no family but the Night’s Watch. By rights it seems she ought to have kept it, or at least passed it on to her heir (though of course it’s lucky that she didn’t, or it would probably be in the hands of the Freys). Yeah, it had probably been traditionally passed from father to son but uh, when has Maege ever given a fuck about the patriarchy before? So I doubt that’s why she didn’t keep it.
Presumably she felt the same way Jeor did - “the very sight of it reminded me of Jorah’s shame” - and just didn’t want it in the house anymore. So she sent House Mormont’s valyrian steel sword to Castle Black, where Jeor hid it away and forgot about it. (Reminder here that Tywin Lannister tried for years to get his hands on an ancestral Valyrian blade, and Jeor Mormont just forgot that he had one lying around.)
It takes a fire to remind him of it - I won’t even touch the fire symbolism here what with Jon possibly being a Targ bastard and Longclaw possibly being Lightbringer because damn - and that fire burns away everything but the Valyrian steel. Basically, everything that connected Longclaw to House Mormont, and symbolically some of the last things that connect Jeor to his house and family as well.
So he looks at what is now just a Valyrian steel blade, and thinks…it’s time to give this thing up once and for all.
And he has the rest of it made anew, with a new pommel (because the bear was nearly indistinguishable anyway), so that this bastard boy he’s having mentor feelings about can earn his honor.
And this is why I warn people not to get attached to Mormonts.