The current aggro system goes like this.
1. closest target to them
2. who is dealing damage
3. top damage dealers
4. who is using a shield / has more toughness and overall armor.
Now I suggest a change to.
1. closest target to them
2. who is using a shield / has more toughness vitality and overall armor.
3. who is dealing damage
4. top damage dealers
This would not only make soldier armor and toughness better in general it would also make these armor sets more useful to their groups rather than just the player using the armor.