How are we to understand Al-Tirmidhi's saying "a good, sound hadith" about a weak hadith, and which opinion should we adopt?

Imam Tirmidhi, the author of "As-Sunan," was known for classifying hadith (definition) into: Sahih (definition) (authentic), Hasan (definition) (good), and Gharib (rare/uncommon). He sometimes combines these descriptions in a single hadith. By Hasan, he means a hadith whose chain of narration is free from accusations of lying and oddness (shudhudh), and which has been narrated through other channels. Scholars have differed regarding his combination of Hasan and Sahih, or Hasan and Gharib. Ibn Taymiyyah holds that for Tirmidhi, Hasan refers to what has been narrated through two channels without accusation or oddness, and a hadith might be Gharib in its chain of narration but Hasan in its text due to multiple corroborating evidences (shawahid). The differences among Imams in hadith criticism are like their differences in jurisprudence; each is a mujtahid (one who strives to form an independent judgment) and will be rewarded. Tirmidhi sometimes shows leniency in declaring a hadith Sahih or Hasan. A specialist relies on proof and evidence, while a non-specialist follows the most trustworthy in religious matters.