This will give some additional nature resistance.
You can also invest in the constitution for more survivability, but I view it more as a waste of points for this type of character as it should be avoiding direct combat. Moreover, after you get Lethality talent it will boost your damage directly. Cunning will boost your songs increasing the bonuses that they provide. Third priority - Cunning - after you have 34 dexterity, put all points into this stat.It will also boost your attack, damage, and defense You will need it to use the best bows in the game and to get all the required talents. Second priority - Dexterity – get it to 34 points.18 points is also an option if you get bonus strength from other equipment: belts, rings, amulets.
You will need it to wear end-game light armor. I suggest this investment into attributes: Moreover, to wear some of the best armors at the end game you will need strength. As Leliana is a rogue, your main attributes are dexterity and cunning.