Not minion buffs. That means shit like Envenom Weapon, Deadly Poison, etc. Any weapon improvements you put on it will be on the weapon forever once you attach them the first time. And I would assume Rummaging Kobold adds a second to your hand. After all, the weapon is still being destroyed; it has to be for the deathrattle to trigger. It just ends in your deck instead of your graveyard afterward. It's hard to be sure without testing, and could easily go either way, but I don't see why the kobold wouldn't interact with this one (though 90% certain that if it does, the one that it generates isn't going to have any buffs on it).