Previously, Vincent had 1 Orichalcum Ore and 3 Mithril Ores within his system inventory and he received them as a reward after completing some hidden missions from his system.
He has been wondering what kind of item he'll make out of these ores and thought of various options like body armor, bracer, shin guard, or anything that could protect his body.
However, with the arrival of his Source Cube, he could just abuse the Protective Suit mode that it has. Although it's expensive, the defense is guaranteed so he wouldn't mind at all. Aside from that, the cube itself can probably be a form of shield already.
Lastly, he knows that he could still increase the capacity limit of his Synthetic Celestial Core within his body.
It's just a matter of time for him to be able to use the armor for a very long duration.