"Bomb damage +2"
The Blast Ring is a Magical Ring that Link acquires in Oracle of Seasons. There is no possible way to acquire the ring in Oracle of Ages directly, but it can be acquired through a Linked Game by using the Ring Secret.
The ring is found within a Treasure Chest on the Western Coast. In order to reach the Treasure Chest, the Pirate Ship must have docked. In order to do this, Link must travel to Subrosia and meet with Cap'n at the House of Pirates. Link needs to acquire the Rusty Bell from Samasa Desert and have the Subrosian Smithy polish it up. This becomes the Pirate's Bell and when given to Cap'n, the Pirate Ship sets sail, docking at the broken bridge in the Western Coast.
Link can then cross the Pirate Ship to reach the other side of the broken bridge. From the Pirate Ship, Link can walk up a screen and right a screen to find a Treasure Chest that contains a Seed Ring. Once appraised, this ends up being the Blast Ring.
When equipped, the Blast Ring increases the amount of damage done by Link's Bombs. This is useful in rooms where there are numerous enemies and a single Bomb can do considerable damage.