As it stands, the Astartes Weapon Specialization talent is a bit weak. No lower than -30 for a given weapon type? That sounds really good, until you realise how rarely that will be useful considering the sheer number of bonuses a space marine is likely to stack on their weapons. Full auto and sights for ranged, charging and hatred for melee to name a few examples. And it costs 1500xp, 1000xp for a tactical marine. Frankly, for the xp there are far better talents or attribute bonuses to pick up.
Thus I propose to add this line to the talent to make it somewhat more useful:
"On a successful attack with the chosen weapon type, the character may add an additional degree of success."
It slightly raises damage and increases the number of hits. What do you all think?