The socket choices are:
Diamond provides a five pound encumbrance reduction for one hour.
Ruby produces a jet of steam which removes a frostbite effect.
Sapphire casts the forage spell.
Pearl casts water walking.
Each socket has a twenty-four hour cooldown, so having a second socket of the same type provides a second use with its own twenty-four hour cooldown.
Diamond encum reductions stack duration, NOT encum reduction.
Also, Baldrics can only be unlocked ONCE this festival.
In the Common language, it reads:
The eisenrucks can be unlocked to tier two during this festival.
Argh I missed that! so Baldrics can be worked once and Eisenrucks twice.