Clerics are proficient with spears, and spears are versatile, meaning it can be used in 2 hands to do 1d8 damage. It is strength based, but I've seen her stats are different in the real game and she can be developed into a Wis/Str build.
There is also the weapon master feat which can bump Str and grant proficiency with longspears, 1d10 damage.
Not to mention all characters can be respec'ced in camp. You could even go cleric/fighter to really trick her out her fighting skill - at expense of spell power. Go eldritch knight to improve spell slots.
