weapon of war, logging axe, kill en masse, peeling (paint off a wall, etc), sparse, faded
劉 centers on cutting or stripping away with a blade: killing en masse, peeling off layers, or using a logging axe. The senses of sparse and faded extend from the idea of something being cut down or worn away.
劉 combines 卯 (a pictograph of splitting or dividing) with 金 (metal) and 刂 (knife), suggesting cutting or killing with a metal blade. The exact historical development is uncertain, but the component combination points to a weapon or cutting action.
The left side shows 卯 (like split halves) over 金 (metal), and the right side is 刂 (knife). Imagine a heavy metal axe splitting logs or a blade peeling paint off a wall, leaving the surface sparse and faded.
For リュウ, picture a logging axe cutting through a tree with a sharp 'ryu' sound, like the hiss of a blade: ryu -> リュウ, and the axe is a weapon of war.