CuCl has more covalent character than NaCl because

NaCl, CuClIn the above molecules covalent nature determined on the basis of electronic configuration. Due to Pseudoinert gas configurationCu+ polarising power is more than Na+. Hence NaCl is ionic CuCl is covalentPolarising power : Cu+ > Na+Cu+ [Ar] 3s2 3p6 3d10 and that of Na+  ...[Ne]Covalent character :CuCl >NaClCations which are having pseudoinert gas configuration [ns2 np6 nd10] posses greater polarising power than the cations which are having inertgas configuration [ns2 np6]Reason : In pseudoinert gas configuration due to the presence of poor shielding d-electrons,nuclear forces of attractions present  till outer most shell. Hence the anion electron cloud readily distorted by cation.