How can he hit Enemies?

When he  had developed the Suit for sustainable to travel around the planet and see if any enemies are threating the city for mass destruction, The villians from the City has planned many events for such specific scenario to occur, the Iron Man is an suit made up of metal capable of flying and having an AI Systems into the brain to perform things done by the human.

the Concepts were first made up with such paper drawn on a list in his own house,then tony started to realize the concepts formally then he started getting right resources from  his AI System in a holographic showing...

The things he done were"
 * Analyzing Concepts
 * Holographic Air building
 * Help from other human beings fucking its manners