Not gonna lie, Steinarr's 'I will burn down half the valley if it means killing Horra' looks increasingly more palatable with every relevation about Horra. Especially if we can't get him outlawed.
Unfortunately, I'm no longer sure he can, at least not easily. Horra himself he can take one on one pretty casually, but this is more backup than I expected, all seemingly successful raiders and old enough to have families, and there are something like a dozen households. Even ignoring the women as a combat threat (which is probably fair), there are probably enough kids old enough to fight to have at least 20 people there who can and will fight us (if, in some cases, not particularly impressive ones...though not all, Hasvir falls under this category, as do the two other sons of Horra we've met...well, assuming the one we met at 12 or so survived).
We, meanwhile, have Us, Abjorn, Stigmar, Stigr, Sten, Abjorn's dad (he's a dick, but he's an old friend of dad's...he'll come), Sten, Steinarr, and potentially Halfdan, and Halfdan's two sons (Aki and his dad might also help, but maybe not if the attack itself is illegal). Can we win that fight? Probably, we're probably more hardcore on average (especially including Steinarr) but we'll likely suffer casualties, and I'd bet good money Horra flees in the confusion (maybe after throwing out some unpleasantness to increase said casualties) and gets away.
We need proof that will hold up in court and to get him to the court in question so he can't just run.