I'll just throw a few ideas out there as if they were true in the context of your world, and see how it goes.

All Sonnlinor have their helms forged by the high priest's forge hammer. No more forge hammer, no more priests for that church.

The church of Moradin emphasized his hand in everyday dwarven activities such as mining, smithing, and engineering, and invoked his blessing when these tasks began. No more forge hammer, no more blessings. No more blessings, no more opening new forges, new mine shafts, or even no starting new (large scale) engineering tasks. The community will die on the vine.

The forge hammer of the high priest is used to consecrate new Hammers of Moradin. The Hammers of Moradin are an elite military order dominated by crusaders and fighting clerics, and dedicated to defending existing dwarven holdings and carving out new dwarven territories. No forge hammer means no new Hammers of Moradin for that city or territory, which means that this elite unit will die out over time.

When a Forge Hammer breaks or goes missing, it is a portent that Moradin is not happy. All senior clergy must go into isolation to contemplate their life, with the exception of the high priest and his two closest apprentices - they will need to venture to the High Church to petition for the right to forge a new hammer. In the mean time, the Church will usually not receive spells above level 3, and the guidance of Moradin (Contact outer plane, Guidance, whatever) will not be given. It is a holy task to construct a Forge Hammer, it is a holy task to maintain a Forge Hammer ... and failing to uphold those tasks will draw the ire of Moradin, warranted or not.

The Forge Hammer of Moradin is used symbolically to 'reforge' paladin candidates to true, full paladins of Moradin. Without the forge hammer, there will be no candidates promoted to paladin status.

The forge hammer is used in any transaction involving a new deal or agreement - that's where expressions such as "hammering out details" and "forging new trade agreements" come from. Without the forge hammer, the Church of Moradin in the city cannot enter any new deals or agreements - possibly to a catastrophic consequence, particularly if there's important peace treaties waiting to be reforged.