i would just call that a shine, you can FBF (frame br frame) animate one, or use a mask in the shape of the thing you are trying to make shiny and then tween your shine shape across it

shines work best when reatively fast, and are quite easy to make, just be sure to use white with an alpha setting of whatever seems good... i wouldnt advise coloured shines but in some cases those can look good aswell