If you go with sustained Dreamforged weapons of any sort- you could have them materialize in the alt equipment slot. It must be unoccupied to function. Error message upon attempting with both slots full: "You must free your mind of distractions- focus by emptying your alt equipment slot."
Switching to the alt slot would be equivalent to your mind altering the reality of your wielded weapons- use some aspect of them to buff the dreamforged ones. Calculated from their base damage and retain on-hit abilities.
Have the first skill devoted to materializing weapons, with the other three providing one-time attacks of some nature that require a dreamforged weapon to execute.
This approach accomplishes several things- Instead of limiting players by forcing them to either use mindstars or be empty handed to use, it actually rewards players by using effective equipment of their choice and builds upon it. It is thematically and effectively different than psiblades because of the versatility of its use and is the only thing that grants access to the further abilities of the tree. It can be used in conjunction with psiblades if one wishes as it builds upon them like any other weapon. Lastly, it's really $#%$ing cool.

Similar to what Greyswandir suggested, have the Dreamforged weapon generated be of the same type as wielded when activated. That would make for some cool builds. Becaaaause- dreamforged weapons use willpower as their main stat! (Possibly willpower and cunning?) I could see a lot of people dumping psiblades because they want to use a dreamforged version of their twohander. While they wouldn't have access to the usual dualwield/one-hander/twohander class trees, the other buffs of Solipsist and the ability to use the rest of the Dreamforge tree could prove quite viable. What do you think?
Edit- on a side note, depending on how powerful you believe this tree would be, you could make the core Dreamforge skill (which allows the other skills to be used) to be either a sustain or something that steadily drains psi per turn.