Seasonal crops
Raise Crop Seed Levels with the Sacred Sword
Use the Sacred Sword on mature crops to harvest seeds and pursue higher-level planting stock for future crops.
Any village development farm with mature crops; use the Sacred Sword on the chosen crop tiles.
Repeat across crop cycles: grow the current seed level, use the Sacred Sword on mature plants, then replant any higher-level seeds you obtain. Each upgrade is chance-based and consumes the mature crop opportunity.
Stop when the desired seed level is reached, or return to ordinary harvesting when produce, village requests or seed quantity is more important than level progression.
Open a guide to find other locations and see what the item is used for.
Use the Sacred Sword on mature crops to harvest seeds and pursue higher-level planting stock for future crops.