The Collaborative International Dictionary of English v.0.48:

Legateship \Leg"ate*ship\ (l[e^]g"[asl]t*sh[i^]p), n.
   The office of a legate.
   [1913 Webster]

WordNet (r) 3.0 (2006):

legateship
    n 1: the post or office of legate [syn: legation,
         legateship]