It is in fact a boarding axe. Here's quick article about them. http://images.google.com/imgres?imgurl=http://www.thepirateking.com/images/weapons_boarding_axe.gif&imgrefurl=http://www.thepirateking.com/historical/boarding_axes.htm&usg=___VMgevjWSn7z1vqeY2W2aij9N5k=&h=250&w=150&sz=6&hl=en&start=8&um=1&tbnid=TqevFGloJj-v5M:&tbnh=111&tbnw=67&prev=/images%3Fq%3Dboarding%2Baxe%26hl%3Den%26rlz%3D1G1GGLQ_ENUS316%26um%3D1 Abusive comment hidden. (Show it anyway.)
http://images.google.com/imgres?imgurl=http://www.thepirateking.com/images/weapons_boarding_axe.gif&imgrefurl=http://www.thepirateking.com/historical/boarding_axes.htm&usg=___VMgevjWSn7z1vqeY2W2aij9N5k=&h=250&w=150&sz=6&hl=en&start=8&um=1&tbnid=TqevFGloJj-v5M:&tbnh=111&tbnw=67&prev=/images%3Fq%3Dboarding%2Baxe%26hl%3Den%26rlz%3D1G1GGLQ_ENUS316%26um%3D1