This is the 2858th most frequent Japanese word.
げ
"げ" is a suffix in Japanese that indicates the appearance or seeming condition of something.
In this sentence, the suffix 'げ' is attached to '自信' (confidence) to indicate a subjective impression of having confidence.
彼は何だか自信げに見える。
He looks somewhat confident.
Here, 'げ' is used with '寂しい' (lonely) to express an impression that she seems lonely.
彼女は寂しげな表情をしていた。
She had a lonely expression.
'げ' here is used with '悪い' (bad) to indicate the appearance or impression of being bad associated with the suggestion.