X Bombs are hefty artillery weapons that people rarely use, it functions like a standard bomb, but it's Asplosion is in a cross shape and has a 50 ft long range. Sounds cool, but in what way would that be useful when no matter how far your standing you may just be disintegrated by your own bomb?
The X Bombs consist of a ball of concentrated Thingamabobium that is kept in a steel shell, throwing the bomb provokes the explosive's Thingamabobium into building up, until the steel shell cannot hold it and it's all released via the openings, creating the blast's cross shape.
They were only ever used somewhere in a cloudy, Heaven like area. We don't know so much other things aside from some angel guy being involved in it.
It is written that these contain a lot of Lamp Oil.