What if i told you there is a way to reach level 20 in crossbow without having to chose crossbow specific trait for your character and without cheating?
Guide to Getting a Crossbow (Step-by-Step)
How It Is in the Current State of the Game
So as you may know currently the game propose only 1 crossbow. There's is more than one crossbow type in the game and you can use them in multiplayer. However in single player we are stuck currently with only one crossbow and in order to use that crossbow you need to be level 20 in the crossbow skill. However unless you tailored your character's story specifically to use crossbow chances are you don't have the required level that would allow you to use the crossbow and from that point you are prety much locked out of it. Forget about tournament or training ground those don't give you XP.
Yes there is a way to farm those level and you don't even need to own a crossbow to do it.
It is fairly simple and you can do fairly early on in the game.
Get yourself a proper army and most importantly get yourself a bunch of crossbow man. Mercenary guards have crossbows and are fairly cheap and easy to find already trained in taverns.
Get and equip a bow and arrow. The stats don't really matter.
Make sure your crossbow mans are at the begining of the list of your army. Don't put more than 5 or 6 of them. After that put some proper close combat soldier.
Find yourself a nice bandit hideout. Don't take one too dificult but also don't take one with too little enemies. You want somewhere between 10 to 15 enemies. 20 if you are brave enough.
Also don't go for forest bandits. Those are generaly composed of longbowmans which are going to be real dificult to deal with. The west coast is generaly filled with hideouts and none of them are forest bandits. Then attack it.
First as you arive make sure there is no bandit in range of your archers then press F4 to tell your archers to fire at will. This will make them draw out their crossbows.
Pull out your bow and find one of your crossbow man. Shoot him in the face until he dies. It should only wound him but he might die.
What you can do now is pressing and holding ALT. This should highlight the items you can pickup on the ground. Grab his crossbow and arrows. Even if you don't have the level the game let you use weapons picked up on the battlefield.
Now press f4 again so your archers hold fire. You don't want them to kill your targets. Use the topography of the map to cheez the game a bit and go do some killin'
Make sure your dudes are not too far in case things get ugly but not too close so that they don't agro the enemy.
When the big boss show up just shoot him in the face too.
Enjoy your new found skill with crossbows!
And sadly the crossbow man that was shot in the face didn't survived the making of this guide.