If I'm oneshotting horses, two shotting light infantry and annoying (doing small damage and stunning) plate guys I think I'm pretty successful. Headshots are oneshot kills. Every time...
I don't know if you saw my build in the Lactose's throwing guide thread... I have 5 IF in my build and it should be just enough. 6 PS, 6PT, 6athletics and 6WM. 130 wpf throwing and 103 wpf 2h. Pretty solid build imo. It actually has some active wpf in throwing too... If I'd gone for bigger PT, I would have lost too much accuracy in the process I think...
I currently have 21/15 build, and no you wouldn't lost accuracy, but movement speed; which is essential for a thrower I see now. Because most of the everyone will be faster than you, even if they have heavy armor. Since throwing is something that requires you to be close to your enemies, but also requires you to get back as fast as possible. I personally wanted to try those throwing lances, so sticked with the build I have. But it has some flaws compared to your 18/18. First of all, you mainly use throwing as a side arm to your melee. Or you utilize them both effectively. But I have to use melee as a side arm to throwing, so my main bread and butter is throwing. Which makes me a pure thrower more often. Well those flaws are:
1-You have to rely on throwing. Well that's not a flaw actually, since it is an effective weapon if you are good at it. But against shielders, there is not much I can do. Yes, all throwing weapons have bonus to shields but that's simply not enough. Imagine you have to fight with a shielder with a build of 15/21, against your 21/15 throwing build. He has 7 athletics and 7 shield skill. So no matter what, he will catch you sooner or later.
So, battle begins. You started to throw some lances or heavy axes at him. Let's say you shot 3, and got succesful with your aiming because you are a good thrower but he blocked them with his shield. Now what? You have to engage him in melee with your, preferably 1 slot weapon. He has the upper hand now and you can't run away from him. If one of his teammate came to help, you are dead. Well now of course your teammate can come to help as well, but this leads us to the second disadvantage.
2-You are a support class and highly rely on your teammates. If your teammates are fucked, you are fucked no matter how good you are. A cavalry will just kill you in the battle, or someone will just stab you from the back, if you do not recieve enough support or your teammates die like flies. So no soloist guy.
If forces are evenly matched, you can support your team to the victory. Perhaps.
3-Horses. Yes you are meant to be a counter for horses, and you can be very good at it. But you are not enough by yourself. You most likely have only 1-2 shots against a good cav player, which is something not enough. They will just charge in, kill one of your teammates, and get away while they just sacrifice some of their horses' health for that kill. If there are no pikeman and archers in your team, you are simply not enough by yourself.
Well, these are my experiments with a
non-loomed 21/15 thrower. I do not know, how +3 throwing weapons are. But throwing is something that includes you to look at ground and pick whatever you find to throw. So that should not be a very big issue after all. Yes throwing can be very effective, but not without a bit of help from the goddess of fortune.
Ok I see this is going to be a wall of text, but let me post my suggestions:
1-Make hard (pure) throwing a bit more effective against
horses and shields. That's all I see as essential. This, and throwing is very fine. Yeah there is no 2, or 3. Just this.