Hornviper Mk II, this is an original weapon. Its original damage is 217, I've upped it to 230. Still not enough, it seems. And another proof of how 'balanced' Vanilla is. Unfortunately it's impossible to fix everything, except for level 9 and 10th.
Firekiss Mk II, that one wasn't changed at all, and I think that here Vanilla is balanced enough. Won't be changed in future either, but don't expect faster firing weapons to have better damage rate.
Salamanca Mk II, yes a good weapon... and also not modified, and when I did try to reduce damage I've got complaints so I reverted it to original. So its fate now depends on your feedback.
And please enlighten me about Sammael, is it a good weapon or not... Yngen's and Onca's feedback on this differs too much.
Next, range is important... in Vanilla, weapons with better range deal less damage. Always. Should stay so in Discovery too. Range is calculated this way (weapon_equip.ini):
[Munition]
lifetime = 1.200000
[Gun]
muzzle_velocity = 500
(example from Firekiss II), multiply values and you get the range. 1.2x500=600. Range should definitely be included here if it's not too much work. muzzle_velocity maybe too, cause it's weapon projectile speed.