Soil erosion poses a critical threat to land productivity and ecological stability, especially in semi-arid regions. In Eritrea, watershed-scale studies that combine spatial modeling with parameter sensitivity analysis remain scarce. This study evaluates the relative sensitivity of individual RUSLE parameters using a previously published GIS-based soil erosion risk assessment for the Mai-Nefhi watershed to better inform conservation planning. The original erosion model estimated annual soil loss ranging from 0 to 250 t ha⁻¹ y⁻¹ (low to severe erosion risk level). A sensitivity analysis was conducted using a One-At-A-Time (OAT) approach, in which each RUSLE factor (R, K, LS, C, and P) was increased by 10% while the other factors were held constant. Results show that the topographic factor (LS) was the most influential, followed by rainfall erosivity (R) and soil erodibility (K). Conversely, cover management (C) and support practice (P) had minimal impact when varied individually. These findings provide a ranked prioritization of erosion factors, offering valuable guidance for targeted soil conservation strategies and sustainable land use planning in environments with limited data. These findings have broader global implications, suggesting that the approach and results from the study area can inform erosion-control strategies in other semi-arid and mountainous regions worldwide.