with a name like swashbucklers mantle,you would think it would be a rogue or warrior item,wis casters would be the last i'd expect to call a "swashbuckler"
Most 'Swashbucklers' were privateers. They came from all walks of life lured to the sea by their dreams of fame and fortune or forced into service for one debt or another. I'm more confused as to why it's limited to just priest classes than why they are included.
2 charges of clicky haste then throw it away. It's lore so you can't vendor recharge it (unless there's a trick with multiple accounts that I don't know about - hmm, interesting...)