Agoge Mufflers +3

Cannot be auctioned, traded, bazaared, or delivered.
Cannot be obtained as a random reward from the Gobbie Mystery Box Special Dial and similar sources.

• Agoge: The agōgē (Greek: ἀγωγή in Attic Greek, or ἀγωγά, agōgá in Doric Greek) was the rigorous education and training program mandated for all male Spartan citizens, except for the firstborn son in the ruling houses, Eurypontid and Agiad. The training involved learning stealth, cultivating loyalty to the Spartan group, military training (e.g., pain tolerance), hunting, dancing, singing, and social (communicating) preparation. The word "agoge" meant rearing in ancient Greek, but in this context generally meant leading, guidance, or training. (Wikipedia)
• Mufflers: In clothing, typically a muffler is a scarf that covers the mouth. Presumably, in this case, it's being used to mean a thing that muffles, ie reduces the noise made whilst using a weapon.