Weapons as Natural Attacks

[Stag]

Is there a way (by feat or w/e) that basically for purposes of abilities, and feats makes it so that the weapons you wield can be counted as natural weapons? This is for a synthesist build I'm working on.

[eggs]

Graft Weapon (http://www.d20pfsrd.com/psionics-unleashed/psionic-powers/g/graft-weapon)? A Dorje would be a bit spendy, but would last a long time.

[Cespenar]

Maybe Daggerspell Shaper, when it gets that ability to effectively fuse his weapons into claws?