Both?
Not all Talents were created equal even if they went by the same title. The Steel Bone Talent Nemesis had now, for example, came from a beast who couldn't make nearly as much use from it. Many creatures born with this talent were only capable of having a small portion of their bodies boosted by this talent.
Nemesis, however, was able to coat every inch of his bones in steel because of this Talent's synergy with his Adept Body. However, there was a limit to what Adept Body could do. Ultimately, this technique was meant for controlling the size of one's body and maintaining its level. This made it quite easy to handle changes to the bone, but if Nemesis wanted to fire longer or more powerful projectiles, it would no longer be related to the Adept Body.
In those cases, it would be more related to bone growth or bone arrow speed, but neither of these things could be controlled by Nemesis' original Talent.