Using the Nokia NbuExplorer, Noki or similar utilities for Nokia phones it should be quite possible to export the contacts from Nokia ARC backup files and save them in form of a vCard file (*.vcf).
Convert Nokia backup archive to vCard contacts file.
We found 2 software records in the database related to .arc to .vcard file format conversion.
Microsoft Windows software - convert arc to vcard on Windows
A small usefull program for exploring and extracting of files created with Nokia PC suite
Convert from arc file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned arc to vcard. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A free explorer for Nokia NBU files