You're assuming that it has to be a sword. The weapon is empathic, meaning that it senses and reacts to your needs, desires and emotions. And even if it fights you for control it's pretty damn awesome just to have. It's not that it's lame, it's just impractical. I got Titan Physiology, do you think that it would be practical to be a 3 story-tall giant with tremendous strength, endurance and whatnot? Hell no. But it would be -blam!-ing awesome while it lasted.