Quenya 

-sta

your

-sta (1) "your", dual 2nd person possessive pronominal ending: "of you two" (VT49:45, 16), cf. -stë (q.v.) Genitive -sto in veryanwesto "of your wedding" (VT49:45) and tengwiesto "of your reading" (VT49:47), allative -stanna in parmastanna "on your book" (VT49:47). An archaic ending of similar form could also be the third person dual "of the two of them" (but according to VT49:51, the corresponding subject ending was changed to -ttë, and then the ending for "their" would presumably become -tta)