I whack animals with the shaft of my javelin (or northern spear if it's winter and I'm not dealing with a trapped animal), constantly aiming for the head. It takes quite some time to whack an unconscious elk on the head before it finally dies, so it provides a fair bit of training, and it seems that melee aimed hits against unconscious targets never miss. That obviously isn't the case when defending against an aggressive predator (or human), where I want the period of danger to be as short as possible. Once I reach 100% in Spear (which will take a long time) I'll switch to another weapon type for "training" combat.
Heh, my guy has 96 in Spear (in his 4th year), and the fight still can take much time. As for elks, it usually takes 1-4 hit for unconscious to die when whacked with the blunt end, in my case, though I must say that it is mostly because while it can't miss apparently, it can hit another part, like foreleg. But knife, with pointy aspect takes at most 4 hit too, so I sometimes prefer it against animal.
Most armour, and animals pelts, are really weak against point damage, while they excel against edge (metal) or blunt (pelt). This is why finishing hits with a knife are devastating, I think. My char has about 75 skill in knife, all of this only thanks to finishers and training by wounded adventurers (who can train in different skills, by knife is probably most often chosen).
Another weapon I sometimes use for training on trapped elks and other big animals is shields (blunt damage). My cow carries 25 shields, I pick it up (which prevents moving, due to weight) and throw at the elk. This sometimes raises Shield skill. It also kills the elk eventually, sometimes before all 25 shields are thrown, and leaves corpse in fair condition.
I generally engage robbers and Njerps with the bow, although robber quests involves dealing with hirelings and trying to keep them alive in the mess that's called battle, so it often starts with a kill of one robber with the bow, followed by a frantic attempt to engage the buggers with the spear, as it tends to be hard to get clear shots (and I make very sure no hirelings have any missile weapons).
It may well be that the small knife preference is indeed a mod one.
You know, I remember the robber quest from some previous version, but haven't encountered one yet with the current character. Don't know what are conditions for it to trigger. I pursue robbers on my own, because I feel the are the only challenge left at this stage. Last in-game month I went for a short trip, which lasted about sixteen days, and encountered FOUR bands of robbers! I wiped them all thanks to my animal shield and bow. My guy wasn't even injured... I have a favourite setup, hide behind a line of three trees (perpendicular to the line of sight to target), which prevents my animals from interfering, and shoot the bow.
Although arrows are far less deadly than javelins, they have much greater range. The bandits are able to shoot arrows being prone, which happens strangely often (even if they have 12+ arrow wounds, like happened in one last case, though unable to walk, for some reason they are still able to shoot).
I don't hire hirerlings, because they annoy me. There is a guy in one village who still demands payment for a job done three years later, even though he can barely walk from all the stuff I gave him. Can you imagine?
Ad for Njerp, I have a policy of attacking only ones which attack me (or the villagers, rare case). When they run, and most of them run, I either let them, or sometimes sneak or just walk behind for fun, leaving them breathless.
Still, the most dangerous guy I fought quite recently was a Njerp, even though it was just after killing four bandits, who didn't impress me so much. The Njerp was apparently a sword master, armed only with a single sword, and no armour except some rags (like a barbarian). He killed one of my dogs in his first move, and then was striking, blocking and countering so skilfully he damaged both my northspear and his bastard sword, and it left me exhausted. I didn't even know that my weapon can be damaged without blocking (I always dodge instead).
But overall, I consider bandits the worst threat, all other being negligible, as long as I have animals to help distract them.