Throwing weapons are one-handed weapons, which means that the Duellist perk increases (+25%) the damage that ignores armour. So, with Duellist and Throwing Mastery, javelins actually do almost as much damage as crossbows, and don’t need to be reloaded! But it’s awkward to create such a build, since you ideally want mastery of a one-handed melee weapon as well, and Quick Hands, and Footwork would be really nice as well, and you have to wait until at least the 7th perk before their damage can be enhanced to crossbow-level …
Throwing weapons (like crossbows) still do only minimal damage to the hit points of fully-armoured orcs, and throwers tend to be vulnerable in melee – but you could also give them a 2-tile weapon for fighting the likes of orcs, so that they can pick off berserkers+young and then still be useful.