Blake didn't know what had caused him to feel like there was a pebble - a lump - something that was stuck in his chest.
He had a general guess that was most likely to be true. That the feeling that he was currently feeling was because of Vera.
It wasn't the feeling of betrayal for telling him and Robus to go on their own way and leaving them nor did he feel that Vera had been cruel to him for doing this to him.
What Vera had told him had made total sense and Blake was able to understand it fairly quickly after he got rid of the initial shock of seeing Vera really did disappear into the sky and leaving him and Robus behind.
He knew what Vera had told him that he and Robus needed the experience to grow stronger was true.
From his exchange with the humanoid demons, Blake knew that albeit his fighting skills were probably not underdeveloped because all he and Robus did back on the island was fight and kill enemies, his other experiences were still lacking.