Abstract: The increasing trend toward larger-scale wind turbines and longer, more flexible blades have made the low-frequency and long-period characteristics of wind turbine blades increasingly pronounced. Consequently, the first-order edgewise bending mode of the blade is prone to large-amplitude vibrations induced by external excitations, which may seriously compromise blade structural safety. Tuned mass damper (TMD) show a considerable potential for suppressing blade edgewise vibration responses; however, conventional TMD may substantially increase the blade self-weight and are difficult to implement effectively within the confined internal space of wind turbine blades. To achieve lightweight and efficient control of blade edgewise vibrations using TMD-based absorbers, this study integrates a lever amplification mechanism and a three-parallel inertial subsystem into a TMD, thereby proposing a dual-enhanced tuned mass damper-inertial (DETMDI). Based on Lagrange’s equations, a controlled dynamic model of a wind turbine blade equipped with the DETMDI is established, and closed-form expressions for the optimal frequency ratio and damping ratio of the DETMDI are derived using fixed-point theory. Numerical analyses are conducted using the NREL 5 MW wind turbine blade as a case study. The research results show that: under a representative lightweight configuration with an additional mass ratio of 5% and a lever amplification ratio of 2, the DETMDI reduces the peak blade-tip edgewise displacement by more than 30%, outperforming conventional TMD and TMDI systems. When the additional mass is reduced by 50%, the dynamic amplification factor of the DETMDI increases by only approximately 15%, indicating low sensitivity to variations in the additional mass. Meanwhile, the DETMDI effectively limits the damper stroke, keeping it within the allowable installation space inside the blade. The results demonstrate that the DETMDI can enhance the control performance for blade edgewise vibration responses under a limited additional physical mass, providing a new technical solution for the lightweight passive vibration mitigation of large-scale wind turbine blades.