The Collaborative International Dictionary of English v.0.48:
Halberdier \Hal`berd*ier"\ (h[o^]`b[~e]rd*[=e]r"), n. [F. hallebardier.] One who is armed with a halberd. --Strype. [1913 Webster]WordNet (r) 3.0 (2006):
halberdier n 1: a guard who carries a halberd (as a symbol of his duty)