The speaker picks up pieces of shattered glass and decides not to throw them away. Holding them in an open palm, they whisper a wish into the cracks and make a quiet vow to the morning sun. The glass is "shattered but yet not broken," which suggests the speaker sees something still whole inside the damage. It reads like a metaphor for healing after hurt, though the poem never says what the hurt was.
Then comes the furnace. The fragments melt and burn, and what comes out is stronger: goblets of "fortified lava." The speaker keeps this new thing close to their heart and reshapes it into something "only i can wield." The last lines look ahead, imagining the treasure given to another "vessel," and to a "hell" not yet experienced. The mood is determined and hopeful, but it carries some fear. The speaker is ready to be changed by pain again, and ready to love anyway.