Does Ultron not have a massive, potentially limitless army of his own? As well as the ability to fly, shoot lasers, and magnetically attract or repel nearby metal objects? And the fact that Ultron is also linked to all his other bodies and the internet (in the movie) means he can keep switching bodies and building new ones indefinitely. Warden has a ton of bodies, a sword, and a head laser. But he's fighting an adamantium death machine with far greater maneuverability and intelligence, who doesn't really have a limit to how many new bodies he can build.