Even with the 1st Sphere Angels gone, Ashton still didn't recklessly barge inside the Palace...
Being careful inside an unknown territory is, after all, never a bad thing. He didn't want to trigger any traps or alarms if he could help it.
Earlier, none of the angels noticed him. This meant that so long as he remains inside the Grand Library, he'll remain unseen and undetected, therefore he'd be safe.
As he went in deeper into the palace, Ashton kept a decent pace.
The Palace was obviously large and very extravagant. Gold and white are the most dominant theme of this place. There are hints of lavishness and nobility everywhere he went. Even the simplest candleholders looked rather expensive in Ashton's eyes.
He also saw some portraits hanging on the walls, which painted a hint of vanity in this rather luxurious place. It seems that the angels aren't immune to these sorts of things either. In fact, they're full of it, honestly.