Some ItemStack tag options like "unbreakble" and "hideFlags" are not given in Spigot 1.8.
When you try to give someone an item with /give and the tag argument, the options unbreakable and hideFlags are being ignored. In vanilla minecraft it works(singleplayer and multiplayer, 1.8 and 1.8.1).

Command I used in vanilla:
/give urtarrila iron_sword 1 0

{HideFlags:63}

Command I used in spigot:
/minecraft:give urtarrila iron_sword 1 0

{HideFlags:63}