Increasing the context weight for the property title, a search word hit in a title will receive a higher rank score than a hit in the body. This causes the item with a search word hit in the title to appear higher up on the search results list. The different managed properties, such as title and body, are mapped into different important levels. The context weight of a managed property is changed in association with the importance level to which it is mapped. So for eg. If you increase the weight of the Project Id then it will only positively affects the ranking score when you search for keywords present in the property. *For any other query the weight has no effect whatsoever!*
when searching for the keywords "Project Id ", the title property weight ensures that the ranking score is boosted for documents having these keywords in the title. But documents without any of these keywords in the title are not boosted by the title weight. This applies to all managed properties of type text.