As a promising renewable energy source, wave energy remains underutilized due to its ultra-low frequency and low power density. To address the limited response capability of conventional energy harvesters under intermittent and irregular excitations, this study proposes an inertial swing-directional rotation conversion strategy based on ultra-lubricated needle roller bearings and develop a frequency-boosting hybrid generator (FBHG) with a pendulum-triggered and bearing-switched configuration. This design ingeniously integrates two directional-rotary triboelectric nanogenerators (TENGs) and a swinging electromagnetic generator (EMG) onto a shared motion source. The innovative structure significantly enhances the output frequency and prolongs the rotation duration, enabling continuous energy harvesting even at an ultra-low frequency of 0.04   Hz. After systematic structural optimization, the rotary TENGs and swinging EMG achieve instantaneous power outputs of 1.26   mW, 1.17   mW and 122   mW, respectively. The TENG can simultaneously illuminate 480 light-emitting diodes (LEDs), while the EMG directly powers four commercial 5   W bulbs. Furthermore, the self-powered system incorporating the FBHG and a three-channel power management circuit (TC-PMC) is constructed to reliably operate a total dissolved solids (TDS) sensor and a Bluetooth-based temperature-humidity sensor, demonstrating the feasibility and practical potential of the FBHG for water quality applications in ultra-low-frequency wave energy harvesting and self-powered environmental monitoring.