You can make small and short very low crawl passage which are only unique and lead into a secret room. There you could hide loot or trophies.
1. No, I haven't had that before. I have attached my logfiles from yesterday. The first should be the one with the missing weapons. I think there was a freeze on the penultimate logfile during the generation of the second round.
https://drive.google.com/open?id=10c36Ussniqo01aUJ5Q6zNqbcuW3EsUYb
2. I don't know anything about the arrow, because I've never used it before or really noticed it. When activating the weapon the display did not blur for a moment. If you like I can make a video with OBS tonight. The side LCD bar on the arm is clearly recognizable by the way.