After reading a lot of feedback and thinking further about interesting traits to play around with. I want add a few new one to the list and mention other ideas which have been posted in other threads.
About squadweapons: in my idea a weapon doesn't scale with squad size. As others pointed out that behavior is well suited for a lot of "officer weaponry" but not always desirable for special weaponry that appears several times in an infantry squad.
So basically we need 2 versions. One, "onepersquad" trait still doesn't scale with squad size and another (keep the "squad weapon" trait name for the new trait) that now scales some by squad size. Maybe one additional per 5 squad members?
Another good request for some units like mines is a "nomorale" trait. Pretty obvious what it should do

Another remark about regeneration trait: it would also be nice to gain a trait where it actually also can revive dead squad members. But maybe keeping both separate maybe...
And to throw some new suggestions into the ring:
unit traits:
"furiouscharge" - the unit gains +25% strength with all its range 0 weapon when attacking adjacent units. If the enemy unit is completely wiped out by the attack the unit moves onto the field the defeated unit was, should it be a legal field that can be normally traversed by the unit.
"defaid" - adjacent units have their defense raised by +20%. Doesn't stack with additional "defaid"-units. Maybe several versions that limit which kind of units are affected (all, infantry, vehicles)
"aimaid" - adjacent units their ranged accuracy raised by +33%. Doesn't stack. Maybe several versions that limit which kind of units are affected (all, infantry, vehicles)
"movaid" - adjacent units have their movement allowance raised by +1. Doesn't stack. maybe several versions that limit which kind of units are affected (all, infantry, vehicles)
"coverace" -raises the effect of cover for the unit by +50%. Can be used to make "ignore-cover" weaponry more important in the game.
"fieldrepairs" - heals hit points of adjacent vehicles, including titans, by a set amount per turn. No "revive". A good range of different strength values would be nice. Great for techmarines and enginseers down the line
weapon traits:
"noreach" - this weapon can't target air units.
"overpower" - this weapon trait grants units having it a second attack per turn. The first attack remains normal, all weapons fire if in range. The second one is an attack where only overpower weapons can attack. Trait to model multi-targeting weapons and the like.
EDIT: deleted my erroneous assumption currently range 0 weapons could hit aircraft units but according to horst that's not the case