Uhm, are we sure Hal's mother was wagered at all? There are a number of ways you might win someone's hand in marriage via a duel which aren't staking the wife like a gold watch in a poker game. Marriage-by-kidnapping customs are quite common historically (and often were ritualised to the point where the wife was "in on it", sometimes not), so Hake may have abducted her and then challenged a would-be-rescuer from her immediate family.
Or there might have been a legal challenge by Hal's mothers relatives which was revolved via a judicial duel.
Also, given he says that Blackhand "had his reasons" for not rescuing them... how sure are we that Blackhand wasn't involved in setting up the duel? Perhaps as a way to avoid a wider feud or an outright war or for some other reason; maybe Blackhand was traded something extremely valuable in exchange or as weregild.
Or there might have been a legal challenge by Hal's mothers relatives which was revolved via a judicial duel.
Also, given he says that Blackhand "had his reasons" for not rescuing them... how sure are we that Blackhand wasn't involved in setting up the duel? Perhaps as a way to avoid a wider feud or an outright war or for some other reason; maybe Blackhand was traded something extremely valuable in exchange or as weregild.