FE3 Arlen, most people just opt to use Merric, because of shinier promo gains, or Linde, for possibly being the most overrated Mage in the series. Arlen does have some distinct advantages over both of them. For one, he has a fantastic weapon level base, trumping both Merric and Linde. And like Merric, he can promote the instant you get him. He also has the highest defensive growths in the game (HP 90%, Def 30%). Now he can’t exactly ORKO the chap 11 wyverns (45 HP at base iirc and shaver having 12 effective might), but Merric can’t exactly OHKO them at base either, so both of them are still going to receive some heavy damage on counterattacks (since dragons ignore all defensive stats). His growths are pretty janky in all other areas, but in the dragon spam chapters he is a great candidate for those scrolls. Wendell might still be the best mage in Book 2, and the only way to save a bishop ring for both Merric and Arlen is through the chapter 5 secret shop, but he can surprise you and is FAR from a low-tier unit in Book 2. (seriously, why hasn’t anyone updated the Book 2 unit rankings)