Answer:
Hades did not tell the other gods about his missing helm of darkness because he knew no god will offer help to retrieve or find it. Moreover, he did not want to appear weak by revealing his most powerful weapon is missing.
His statement seems to suggest that he is treated inferior or even taken to be lesser than his other god siblings. They may be all gods and equals, but his words suggest that his power and authority is taken to be lesser than the other gods.
Explanation:
Rick Riordan's "The Lightning Thief" is part of the Percy Jackson series, a mythical tale of the gods and their adventures. This book is the first part of the series where Percy Jackson, the son of Poseidon, had to retrieve a stolen thunderbolt and prevent an all out war between the gods.
Hades revealed that while Poseidon's bolt was stolen, his "helm of darkness" was also missing. He revealed that he did not tell any of the gods about the missing power because, according to him "I had no illusions that anyone on Olympus would offer me the slightest justice, the slightest help. I can ill afford for word to get out that my most powerful weapon of fear is missing."
This shows how 'inferior' among the gods he is or how the other gods think little of him. He seems to be the least favorite among his siblings, even though they are all gods in the same way, just in different realms.
