The mythical elf had a blue-skinned appearance that looked both mysterious and beautiful.

blue-skinned 是由形容词 blue（蓝色的）和名词 skin（皮肤）加上后缀 -ed 组成的复合形容词，表示"有蓝色皮肤的"。这种构词方式常用于描述人或动物的外貌特征。