Removes sulfate groups from chondroitin-4-sulfate (C4S) and regulates its degradation (PubMed:24311516). In the central nervous system, is a regulator of neurite outgrowth and neuronal plasticity, acting through the control of sulfate glycosaminoglycans and neurocan levels (PubMed:24311516). Involved in the regulation of cell adhesion, cell migration and invasion in colonic epithelium (By similarity). Hydrolysis of the 4-sulfate groups of the N-acetyl-D-galactosamine 4-sulfate units of chondroitin sulfate and dermatan sulfate. Binds 1 Ca(2+) ion per subunit. Inhibited by ethanol. Homodimer. Defects in Arsb are the cause of mucopolysaccharidosis type VI (MPS-VI) (PubMed:8575749). Belongs to the sulfatase family.