We develop a joint geometric and scalar barrier framework for an effective static black hole geometry containing a regular core scale, a finite range dark sector term with amplitude \(\sigma _\textrm{d}\) and inverse range \(\nu _\textrm{d}\) . The lapse function is treated as a phenomenological near horizon and exterior parameterization rather than as a solution derived from a unique microscopic action. We derive the horizon structure, reconstruct the supporting effective stress tensor, and compute the photon sphere, critical impact parameter, innermost stable circular orbit, radiative efficiency, and scalar WKB barrier response. Over the explored regular de Sitter core branch, the core scale gives the dominant strong field shift: it moves the photon sphere and ISCO inward, reduces the critical impact parameter, increases the radiative efficiency, and changes the scalar potential barrier. The finite range dark sector term gives a smaller residual contribution whose inverse range controls whether the deformation reaches the photon ring, ISCO, or scalar potential peak. An explicit pair of parameter triples with the same critical impact parameter to numerical precision is separated by the timelike and scalar channels, and a sector reduced dimensionless local sensitivity matrix has numerical rank three at a representative point. The local inverse problem remains poorly conditioned along the weakest parameter combination, so the result establishes local model identifiability rather than an observational parameter forecast. The spectral sector is interpreted as a scalar test field diagnostic, not as a precision gravitational ringdown prediction.
