Power Ring L-1
"Sword damage +1, Damage taken +1"
In Oracle of Seasons, the Power Ring can be found within the Explorer's Crypt, the seventh dungeon of the game. It is found as a Seed Ring within a treasure chest one screen north and one screen east of the dungeon's entrance. Defeat the two Zol and the three Shrouded Stalfos to cause a treasure chest to appear at the northeast part of the room, containing the Seed Ring.
In Oracle of Ages, the Power Ring can be found within Spirit's Grave, the first dungeon of the game. In one of the early rooms of the dungeon, Link will find himself in an area with a door heading in each direction. There is a pushable block in the center of the room that will open the doors in the room. On the left side of this room, there is a treasure chest containing the Compass. Use an Ember Seed against the wall to the left to reveal a secret. Continue to the next room and step on the switch to reveal a treasure chest. Open it up to get the Seed Ring that becomes the L-1 Power Ring when appraised.
When worn the Power Ring L-1 will increase the damage done by Link's Sword by one unit. However, it will increase the damage done by enemy attacks by one unit. This is a trade-off and is most useful if you aren't worried about your life meter. It should be used with caution as damage accumulates quickly.