Eutectic high entropy alloys (EHEAs) combine the high configurational entropy of HEAs with the thermodynamic stability of eutectic microstructures, offering a promising pathway toward high-temperature structural materials for fusion systems. In this work, a series of reduced-activation FeCrVTax (x = 0-0.7) EHEAs were systematically designed and investigated. CALPHAD modeling, validated by XRD and SEM-EDS analyses, confirms that the alloys solidify into a dual-phase lamellar structure composed of a BCC Cr-V-rich matrix and a C14-type (Fe, Cr)2Ta Laves phase. Among them, the hypoeutectic FeCrVTa0.2 alloy exhibits the most favorable balance of strength and ductility, attributable to semi-coherent BCC/Laves interfaces with moderate lattice misfit that simultaneously impede dislocation motion and serve as efficient sinks for irradiation-induced point defects. Under high-dose Au+ ions irradiation, FeCrVTa0.2 demonstrates excellent resistance to void swelling. Meanwhile, the Fe2Ta Laves phase undergoes selective amorphization, while the BCC matrix remains crystalline. The present findings extend this self-healing concept to eutectic systems, revealing that lattice misfit at semi-coherent interfaces functions as a key design parameter that concurrently optimizes mechanical performance and irradiation tolerance. These insights provide a mechanistic basis for developing next-generation, low-activation EHEAs for fusion reactor applications.