Word Origin and History for have something his sleeve
O.E. sliefe (W.Saxon), slefe (Mercian), from P.Gmc. *slaubjon (cf. M.L.G. sloven "to dress carelessly," O.H.G. sloufen "to put on or off"). Related to O.E. sliefan "put on (clothes)" and slupan "to slip, glide," from PIE base *sleubh- "to slide, slip." (cf. expression to slip into "to dress in"). Mechanical sense is attested from 1864. To have something up one's sleeve is recorded from c.1500. Meaning "the English Channel" translates Fr. La Manche.