Switch Weapon/Passive Tree Post Casting but Prior to Damage

Say I play as mercenary and have invested in 2 trees:

Tree 1: focus on grenade damage

Tree 2: focus on bolt damage

Now I bind skills on two different weapons, which corresponding to tree 1 and 2

Weapon 1 (Tree 1): link to gas grenade

Weapon 2 (Tree 2): link to explosive shot

In action I throw the grenades using Weapon 1 and switch to Weapon 2 to fire explosive shot for detonation. So what will be the situation:

Does the gas grenade take all the benefits from Tree 1 (grenade focused) because it has been thrown out? Or,

Does the gas grenade loses all the damage traits from Tree 1 because I have switched to Tree 2 for bolt detonation?

I guess it all comes down to when the damage multipliers are being allocated for calculation?