Item's still deteriorate with or without repair functions, but i do not see harm in 100% repairs, heck could even throw this item in Shylas shop for end game preservation builds for red coins or a decent amount of gold.
https://wiki.mabinogiworld.com/view/Platinum_Hammer_of_Durability
or even throwing this in would be a start to:
https://wiki.mabinogiworld.com/view/Repair_Protection_Potion