The effects of atmospheric pressure plasma treatment and the tightness factor on the low-stress mechanical properties of weft-knitted wool fabrics were evaluated using the Kawabata Evaluation System for Fabric (KES-F). The statistical analysis showed that the plasma treatment and the tightness factor had significant effects on the fabric low-stress mechanical properties (p-value < 0.05). Plasma-treated fabrics showed significantly higher bending and shear rigidity and hysteresis, compression energy, thickness, compressibility, surface friction and lower compression resilience and geometrical roughness values compared with untreated fabrics. An increase in the fabric tightness factor significantly increased fabric thickness, bending and shear rigidity and hysteresis, and decreased tensile extensibility and geometrical roughness. The relationship between primary handle attributes evaluated by Wool HandleMeter and KES-F mechanical properties was also investigated. The results confirmed a highly linear correlation between these two sets of data, where rough/smooth and hard/soft attributes evaluated by the Wool HandleMeter had the highest correlation with bending rigidity, shear properties and bending hysteresis, as measured by the KES-F.