The ghost has been stated to be a plot element, so discussing him would reveal story details. And enemy equipment has been described, just not in extreme detail. For example, we know Fallen weapons in good detail, and know weapons that the Hive wield. Plus, you can envision the types of weapons enemies will wield in accordance to their culture. Cabal could utilize launchers and other heavy equipment in addition to their Gatling guns. And the Vex are from alternate times, so you can expect some cool stuff.