Logs are like the history of graal era recorded in one big batch of text, say I brought a gun it would be like (this isn't what it looks like but it would be LIKE)
Olirus id****** brought gun 07:57 used to have 125000 gralats, now has 5000 gralats
This lets us also track things which happen such as hacks and cheating and player abuse etc
They are items that were tested as part of an unreleased project. They are items, they do nothing. If you think it is cool to have them due to rareness okay, but they serve no purpose.