This study employs a benchmarked Discrete Element Method model to investigate the influence of particle shape on the compressibility behavior of granular assemblies within a controlled comparative framework. Twenty idealized particle geometries with different shape characteristics were analyzed under constrained compression at vertical stress levels ranging from 0.1 to 3.2 MPa. Macro- and micro-scale responses were evaluated using constrained modulus and average coordination number, together with additional contact-scale analyses to improve the interpretation of particle-scale behavior. The results indicate that both macro- and micro-scale responses remain strongly stress-dependent, suggesting that conventional indicators alone cannot fully isolate particle-shape effects. A stress-normalized scaling approach was therefore applied to reduce the dominant influence of stress and clarify geometry-related trends. The analyses demonstrate that increasing particle irregularity promotes denser contact networks, redistributes contact forces across more contacts, and alters local deformation mechanisms. The findings provide a comparative DEM-based assessment of shape-dependent compressibility and contact-scale force-deformation behavior in idealized granular assemblies.