Thor's Hammer- I'm not really sure about the implication on this part if we remove Pneuma so i'd be neutral on this. But I'm also wondering why they were given the skill. Any info from the higher ups would be nice.
Tyr's Shuriken- The damage is ok i guess. i was able to survive a spam of a ninja using a Gunslinger. But i also agree with you on buffing the other skills of ninja.
Gun Slinger Bullets- The elite bullets have Neutral, Holy, Earth, Fire, Wind, Water. If element mods where not to work on Gunslinger, i think using Angeling Card or holy armor will weaken their damage so much providing no gameplay while being against Gunslingers. (Just Wear Angeling and Ranged Reduction or Nullification Equipments)
Suggetion for a new stalker sword- I agree with this. But it should be Str Based not Dex. Coz if the damage we're dex based it would be just buff the dex build stalker leaving again the int build stalker far behind. Also i haven't seen any sword which has a dex based damage. But as the GM's said this is not on Top Priority.
For the stats im thinking something like this. Buff Damage on Back Stab and Envenom. Back stab should only be casted once in the back then it can be spammed even if the enemy is already facing you (i think this is how the skill works the first time it was introduce, but i think there were bugs depending on the position on the map) and add some stun lock as well (Like AB and Sonic Blow). Some Bonus on Str Dex Agi Vit ASPD and HP. (Sounds like a lot of work >.<)
Just My Opinion.