Based on the cesium 6S_1/2(F=4)→ 6P_3/2 → 8S_1/2 → 7P_3/2 → 6S_1/2(F=4) diamond-type energy level system, coherent and collimated blue light (CBL) at 456 nm (7P_3/2 → 6S_1/2) is generated via a four-wave mixing (FWM) process, driven by the stepwise excitation with two pump beams at 852 nm (6S_1/2 → 6P_3/2) and 795 nm (6P_3/2 → 8S_1/2). In the experiment, when the two pump beams propagate through a hot cesium vapor in a near-collinear, co-propagating single-pass configuration, a portion of the generated CBL is used as a seed light and injected into a four-mirror ring optical cavity, successfully achieving cavity-enhanced CBL output. Compared with the single-pass configuration without a cavity, the output power of the cavity-enhanced CBL is increased by nearly one order of magnitude. In particular, the polarization measurements for CBL using two sets of cavity-enhanced CBL spectra have further revealed the polarization characteristics of CBL, offering new insights relative to previous studies. Moreover, by controlling the polarization of the intracavity seed blue light, effective manipulation of the output CBL polarization has been achieved. These findings provide important experimental evidence for a deeper understanding of the physical mechanisms underlying CBL generation. Additionally, the use of an optical cavity helps to narrow the linewidth of the CBL. Such a narrow-linewidth and frequency-tunable CBL has potential applications in some quantum optics experiments and underwater free-space optical communications, among other fields.