Although the box art features an AC wielding two firearms, such a feature would not become available until Armored Core 3 where howitzers and flamethrowers are assigned to the left arm.
Mr. Keepless - Jetter, is an Raven from Armored Core: Last Raven Arena and is the Replica from the Armored Core Cover.
This game Armored Core is exclusive on the Japan Playstation Classic Mini Console bundled with 20 games.