Goblin Slayer does take off his helmet in the manga. However, it's not a frequent occurrence and is often tied to specific story events that add depth to the narrative.
I'm not entirely sure of the specific moment in the light novel when he takes off his helmet. It could be during a moment of rest or when he is in a relatively safe environment with people he trusts.
Taking off his helmet in the light novel could potentially be a turning point in his character development. Maybe it's a step towards him becoming more open and less consumed by his single - minded focus on slaying goblins. It could also be a way to humanize him more to the other characters in the story.
Goblin Slayer manga is indeed ongoing. It continues to captivate readers with its unique plot and character arcs. The creators are committed to bringing more exciting content.
One idea could be a crossover with 'Sword Art Online'. The Goblin Slayer could be transported into the virtual world of SAO where he has to deal with goblin - like mobs in a different gaming environment. He might use his unique skills and no - nonsense attitude to clear floors and quests in the game.