The origin of half-metallicity, structural, thermoelectric, elasto-mechanical, and thermodynamic properties of Co2ScSb and Co2TiSb full-Heuslers has been examined by full potential methods. Structural optimizations support the stability of both alloys in AlCu2Mn-prototype with space symmetry of Fm3 over bar m (#225) space group. The occurrence of perfect band occupation and interpretation of density of states through the modified version of the Becke Johnson (mBJ) scheme for both these Heusler systems delivers more precise and accurate results rather than GGA and GGA + U. The density of states and band occupation describes the semiconducting nature with an indirect band-gap 1.08 eV for Co2ScSb and 1.32 eV Co2TiSb. Robustness of various elastic constants against external forces is checked to descripted stability of these alloys. The evaluation of elastic constants and its other associated mechanical constituents reveals ductile behavior along with high melting temperature. The thermoelectric coefficients are used to check the applicability of the material for waste heat recovery systems and technological purposes. Thermal parameters support the material's low anharmonicity and hence predict the stability of these alloys at the wide range of temperatures and pressure. The thermoelectric parameters pose its applications and stand to develop devices based on spintronics and thermoelectric purposes.