As Kazuma becomes cautious about Darkness' odd behavior, her thief friend Chris offers to teach him a Steal skill, which he inadvertently uses to steal girls' panties. Later, the entire town is brought together to defeat an army of cabbage monsters for the harvest, where Darkness demonstrates her ability to withstand enemy attacks while also showing off her nature as a masochist.
In the Light Novel, Aqua explicitly taught Kazuma her party trick skill Nature's Beauty, while Kazuma only saw Aqua performing the skill in the Anime. In both instances though, Kazuma decided NOT to learn the skill due to the high skill point cost and the useless nature of the skills.
Chris also taught Kazuma the thief skills "Hide" and "Detect Enemy," but that is not as obvious in the Anime.
Kazuma did not do the victory swings with Chris' panty in Light Novel. However, the LN version is not much better off, as Kazuma still threaten to make the panty a family heirloom and swindled all Chris' money.
In the Light Novel, Chris originally wore skirts, and ultimately decided to switch to shorts after the panty instance. In the Anime, Chris always wore shorts and did not do any outfit change.