Hypothesis
"Relax, farming that guy will be easy for me," Rain said. "Until the others will obtain the power to do the same, I will have all this time to do that alone."
Rain wanted to test the limits of the levels of the skills in that system, but since he was obsessed with efficiency and confirmed that creating copies of the same weapon himself was fifty percent more expensive, he resumed his task of collecting more different weapons from the next day onward.
Whenever he showed up inside the castle, the king would use all the tricks possible to defeat him. He made his monsters even bigger and granted them more shadow to make them tougher. Still, Rain leveled up the Fire Blade for that reason… when he used the spell on Elisabetha, the ominous sword would decrease the shadows with every single strike. Usually, it doesn't take more than two strikes to kill each of the summoned creatures.