Non-5* unique characters have pretty good skills anyway if you raise them to 5*.
The Cordelia 5* I have wields the Brave Lance+ so she can attack 4 times if she is faster than the enemy and, she has the skill Galeforce which Lyn also has, this allows you act twice during a turn if you initiate an attack against something, you get to move again after.
Gunter has the skill Harsh Penalty, did you get attacked by a thief and had your stats lowered? Harsh Penalty reverses it and it becomes a buff for you.
I just got Draug. He has some good skills, odd weapon choice though. Zero speed and wielding a Brave Sword? He needs to be faster to hit multiple times. He also has the skill Lunge, and Pavise: Reduces damage by 50% against adjacent enemies.