This paper presents an enhanced concatenative synthesis framework for Brazilian Sign Language (Libras) based on motion-capture (MoCap) data. The proposed method extends previous work by incorporating movement dynamics into the unit-selection process, allowing fragment selection to consider both pose similarity and velocity continuity. In addition, a quaternion-based transition smoothing mechanism is introduced to reduce discontinuities between independently recorded sign segments. The framework also employs a compact quaternion-only motion representation and a web-native architecture for real-time synthesis and visualization.