Oliver

I'd sooner play Blarowl+def, CC, and atk ploy than a blade tome when I have 20 spd. As you said, his def is actually half decent, especially if you take into account the ploy and the owl spurs and his fat HP pool

Yeah, no. Putting Close Counter on a mage with limited merge potential is pointless. Wasting high arena weight fodder on a unit you can’t merge is a terrible idea

Assuming Atk Ploy + Close Defense he has an effective 34 Def, with 42 HP. This means he dies to 2 neutral (lance) hits of 55, or less than that with a special. This just isn't enough in my opinion to be worth giving him that skill, and I don't consider Close Counter worth putting on units that I don't expect to be able to tank their own color.

I also wouldn't put such a valuable skill on units that can't be merged reliably. As far as I'm concerned, Oliver is Atk Ploy fodder. His low Spd and Atk make using him on the player phase impossible. For enemy phase mages, I consider Raven/TA or Owl/CC to be the only viable options. While he can run the latter set reasonably well, there are plenty of better options and I think that's a lot of investment unless you're absolutely set on using him.