A "fear" effect? That doesn't seem to make much sense. Who would be more fearful in one-on-one, the heavily armored knight, or the armor-piercing crossbowmen? ...Bullet through butter...
-Decrease the walk/run speed by at most 1/3 WHILE aiming and it should make things a little more balanced. An accuracy decrease takes effect when moving, but an actual penalty on movement would further balance bow and x-bow "situations". Did people ever shoot, re-load bows while running?
-The time difference for re-loading different quality ranged weapons seems minimal. How about increasing the time it takes to load more powerful x-bows and bows, up to a maximum of 2 additional seconds for the siege x-bow, and maybe 1-2 seconds for the war-bow. Longbow already has a brutal re-load time. Historically, weren't longbows used to fire a quick succession of arrows? And their accuracy was abysmal? Correct me if I'm wrong.
-A longer animation for "prepping" the throw of a javelin, axe, etc. would solve the insta-throw problem.
Keep in mind these are just rough suggestions, mutilate them at your desire.