Thou shalt also decree
gazar (gaw-zar')
to cut down or off; (figuratively) to destroy, divide, exclude, or decide -- cut down (off), decree, divide, snatch.
a thing
'omer (o'-mer)
promise, speech, thing, word.
and it shall be established
quwm (koom)
to rise (in various applications, literal, figurative, intensive and causative)
unto thee and the light
'owr (ore)
illumination or (concrete) luminary (in every sense, including lightning, happiness, etc.) -- bright, clear, + day, light (-ning), morning, sun.
shall shine
nagahh (naw-gah')
to glitter; causatively, to illuminate -- (en-)lighten, (cause to) shine.
upon thy ways
derek (deh'-rek)
a road (as trodden); figuratively, a course of life or mode of action, often adverb