Adjusting the values of arguments is a widely applied method to establish the semantics of argumentation frameworks (AFs). In this process, the influence of a single attacker's value is mentioned or implicitly used many times. However, this effect has not been studied specifically. As a result, its role in semantic exploration cannot be brought into full play. Thus, my objective was to study this effect, so as to provide a new tool for semantics research. In this paper, the strength of this influence was called the relative attack strength (RAS). It was formally defined and computed by a three-variable function $ras$. Then, nine basic properties of RAS were studied. As an application, I established a new semantics for fuzzy AFs based on RAS, which covered the Gödel semantics. The main contribution lies in the proposal of RAS and the discussion of its properties. This provides a new tool for the further study of argumentation semantics. The other contribution is the establishment of new semantics. On one hand, it fills a gap in theory. On the other hand, it shows the effectiveness of RAS in semantic research of AFs.