FIG. 1 is a perspective view of the handrail post of the present invention, the broken lines show environment and forms no part of the claimed design; FIG. 2 is a front view thereof, with the rear view being identical; FIG. 3 is a top plan view thereof; FIG. 4 is a bottom plan view thereof; and, FIG. 5 is a side view thereof, with the reverse side view being identical, the broken lines show environment and forms no part of the claimed design.