Noncollinear antiferromagnets (NCAFs) offer an ideal platform for high-performance spintronic devices. Weak spin-orbit coupling (SOC) magnets, though abundant and important, are overlooked. We propose a symmetry framework for two-dimensional triangular antiferromagnets with ${120}^{\circ }$ spin configurations, exploring multi-degree-of-freedom coexistence, coupling, and manipulation in the weak SOC regime. Symmetry analysis reveals the spin chirality driven ferroelectricity, Berry curvature, and antiferromagnetic-induced spin splitting—beyond magnetic or spin space group descriptions—coupled via an inversion-induced spin-chirality transformation. The coexistence and coupling of these properties remain regardless of the in-plane rotation of ${120}^{\circ }$ spin configurations. Ferroelectric polarization reversal will switch spin chirality, Berry curvature, and spin splitting, enabling nonvolatile electric manipulation. Spin canting further breaks effective time-reversal symmetry, introducing unconventional SOC-independent valley polarization as an additional coupled degree of freedom. Multiple functionalities, including magnetoelectric coupling, circular dichroic Hall effect, nonrelativistic anisotropic Edelstein effect, and anomalous valley Hall effect, are enabled. High-throughput calculations on triangular-lattice MXenes identify monolayer ${\mathrm{Zr}}_2{\mathrm{VC}}_2{X}_2$ ($X=\text{F}$, Cl, Br, I) as promising candidates hosting ${120}^{\circ }$ spin configurations. First-principles calculations exemplified by ${\mathrm{Zr}}_2{\mathrm{VC}}_2{\mathrm{Cl}}_2$ validate the predicted tunability and multifunctionality. This work establishes a symmetry-guided framework for NCAF-based spintronic devices with tunable multifunctionality.

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• Ferroelectricity
• First-principles calculations
• Multiferroics
• Spin polarization
• Spintronics
• Valleytronics
• 2-dimensional systems
• Chiral magnets
• Noncollinear magnets
• Symmetries in condensed matter