Assume that you've conquered the issue of floatation, probably using some very-much-lighter-than-air gas bladder, allowing your ships to take to the skies.

Assume also that you've invented a way to maneuver effectively in the air using only the wind and sails. The sail (or hull) design isn't necessarily identical to ships of the age of sail, but is limited to that level of technology/materials.

Most importantly, assume that traditional age of sail canons are not possible due to the sheer weight of the metal shot & barrels (and powder too, I guess). The ship can indeed float, but we do have to be relatively weight conscious. I would allow a bit of flexibility here in terms of what was known/possible in the age of sail.

What are some other possible forms of weaponry that these air ships could use to do battle in the skies? And what would you use to defend against that suggested weapon?