Heirlooming throwing weapons should bring higher shot speed, too, like in bows, i think. It should be slight buff, like 1 point, or 2:
Now it looks like that:
weight 4
requirement 3
spd rtng 89
shoot speed 20
thrust damage 34 pierce
max ammo 4
weapon length 76
accuracy 102
Bonus against Shield
Secondary Mode
Gen1= 88spd 20shspd 36pierce
4ammo
Gen2= 90spd 20shspd 36pierce
4ammo
Gen3= 90spd 20shspd 36pierce
5ammo
I think it should be:
weight 4
requirement 3
spd rtng 89
shoot speed 20
thrust damage 34 pierce
max ammo 4
weapon length 76
accuracy 102
Bonus against Shield
Secondary Mode
Gen1= 88spd 20shspd 36pierce
4ammo
Gen2= 90spd 21shspd 36pierce
4ammo
Gen3= 90spd 22/23shspd 36pierce
5ammo
etc.