The various stages of Umi Ryuuzaki 's sword throughout the series.
Stage One features a large white-ish egg shape as it's central part, indicitive of Umi just starting out as a future Magic Knight . This shall remain a central part throughout the rest of its evolutional line.
Stage Two features a large circular saphire as it's centerpiece, representing Umi's connection to the element of water. Surrounding the central jewel can be seen a small, dragon-like figure, depicting her finally starting to grow and become a true Magic Knight.
Stage Three features a larger, more mature dragon curling its head back to face towards the handle segment. This is accompanied by a dark handgaurd in the shape of a wing coming from its back. This signifies Umi's continued growth and progress to fully becoming a Magic Knight.
Stage Four, The Final Stage, has a fully grown dragon in the image of the Rune God , Water Dragon Celes , facing the weilder with his snout over the jewel pointing toward the blade. Other features include an addition handguard putting one on each side in the detailed shape of Celes' wings. The evolution into this form say's that Umi has finally achieved, at least in mental capacity, skill, and character, the vaunted status of Magic Knight.