According to the official happy dungeons website the awakening materials required to upgrade your weapons can only be found in the infinite dungeon. So once you max out your items level you will have to play infinite dungeon to get the required materials. I personally have not found any of these yet but, they should appear as a toolbox looking item and show up under the ring (accesory) items in the menus after you pick them up in game.https://www.happydungeons.net/news/info/754/
According to ThaDevilzhand, the gold chest on leven 25 seems to have a better drop rate then other locations (possibly just luck though)
Thanks to steamboat wi11y for the following: just to add to your guide, when farming these on B2 chest (behind the breakable wall) do the following;
Start the dungeon (preferably solo),
Run and break the wall, ignore enemies,
Pop the chest, check drops,
If you do not get a toolbox, jump off the side of the map, quit and restart.
Takes about a minute. If you get a drop you want, finish the dungeon.
On a side note: might be quicker to exit the dungeon and restart via the menu option?