Powers and Princips are not mentioned in the old testament and therefore have no direct hebrew equivalent. my suggestions might be close in literal meaning, but are not canonical AFAIK.
Power/Authority: there are few hebrew synonyms, of which the only one whose plural form ends with -im is: Tokef/Tokeph.
a more accurate english equivalent qould be "validity" (also attacker/attacking, though that's besides the point). that's the best I got, though.
Principality (princedom) is Nesichut, pl. nesichuyot.. next.
Prince - Nasich / Nasikh (ends with a phonetic X sound. i.e. Xalapeño)
plural is Nesichim, so the meaning may be close enough and the sound fits.
alternatively, Ruler (another translation of principatus) in hebrew is Shalit. pl. Shalitim
hope it helps.