Without further ado:
unit traits:
"sequentialmovement" - or could be just called scout trait

"disorderly" - The unit with this traits suffers from frequent disorder among it's ranks and is generally poorly lead. The unit loses morale at the double rate. Great trait for a lot of ork units, hive militia etc.
"IgnoreZOC" - Unit ignores Zone of Control of enemy untis and can move freely even partially surrounded. Would be a great trait for air units.
"FastDisembarkment" - the unit can disembark at any time regardless of how many movement points have been spend. So basically the infantry unit can move with the full movement allowance of the transport but then attack with their own weapons.
"regeneration X" - be it because of superior physical capabilities or by technology. The unit repairs/regenerates X wounds per round. Does not revive already dead squad members. This provides a possible implementation of regenerative void shields for titans and for modders a nice tool for further races that have "regeneration powers" of some sort (tyranids *cough* etc...). If a trait with variable is too annoying to implement then pls provide a good range. Something like reg 1, 2 and 4, would be nice.
"flanker" - the unit is adapt in outflanking the enemy. When the unit attacks the target can't retaliate. Nice trait to use for fast units like flyers and rough riders, to limit their causalities. Might also be used to units like ratlings and Space Marine scouts as they prefer to attack from hidden.
"fear" - all adjacent enemies of the unit with this trait lose morale per turn. Great trait to represent monstrous beasts of other 40k races (chaos, anyone?

"neveralone" - the unit doesn't like to stay alone on the field and prefers to gang up on enemies. When not adjacent to a friendly unit it will constantly lose morale per turn. Great for "swarm units" like ork gretchins or others *cough*...
weapon traits:
"effectiveagainst{unitclassindex}" - the weapon gains +100% strength against targets of a certain unit class. Great for implementing real sniper weapons which a great against infantry but not so much against everything else, also for anti-tank weapons that don't hit so hard against infantry. a great implementation would be with {unitclassindex} is some form of array. So for instance "effectiveagainst{0,1}" would mean the trait works against units of the unitclassindex 0 and 1 (currently infantry and heavy infantry). If this implementation is too annoying, then pls provide following: a trait to be effective against the unit classes IDs 0 and 1 (infantry), effective against the IDs 2 to 12 without 10 (mechanical units without stationary), also for titans (ID = 11) and flyers (ID = 9).
"ineffectiveagainst{unitclassindex}" - opposite of "effectiveagainst{unitclassindex}". -50% strength against targets the weapon is weak against. Implementation similar to "effectiveagainst{unitclassindex}".
"getshot" - the weapon is unstable and can malfunction. On every shot calculated there is a chance of ~10% to cause one wound on the weapon user. Trait for the beloved plasma guns

"squadweapon" - the weapon is a squad support weapon. Number of shots don't scale with squad size. As long as 1 member of the squad exists it is assumed the squad weapon is still functional. Very important for the implementation of infantry with heavy weapons choices or squad leader weapons...
"moveorshot" - weapons with this trait cannot be fired after the unit has moved. Great trait for heavy artillery units to represent the setup phase of said unit.
"blastweapon" - When used against units with unitclassindex 0 and 1 (infantry), the number of shots is doubled. Good trait for all explosive weaponry which are particularly effective against masses of infantry. implementation could also be similar like i requested for "effectiveagainst{unitclassindex}" for more flexibility for modders.
"heavyhits" - each weapon hit causes x2 number of wounds. Trait to properly implement low rate of fire weapons that have devastating effects on the enemy if they hit.
"dweapon" also known as Titan-Killers

... puh. quite a list. But if everything is implemented i think i could basically mod everything the imperial guard, space marines and orks have to offer in their weaponry. And in that regard also from all the other races of the 40k universe.