Kill Scarmiglione both times and this will be yours. Two easy fights if you keep Palom and Porom casting their twin magic. Use Tellah as a healer to keep them alive. if Cecil hasn't reached lv25 by the end of the battle head back and grind, You will become a Paladin if you continue forward and interact with the pillar. which make you miss these achievement for this game unless you load an older save.