I read somewhere that the combination of weapons in the four hands of Vishnu's chaturvyuha avatars results in 4 factorial or 24 combinations of Vishnu's tattvas but what do each of these signify?
First of all, let me clarify that Vyuhas are not Avataras like Rama and Krishna. In the five fold expansions of Lord Vasudeva mentioned in Pancharatra agama viz. Para, Vyuha, Vibhava, Archa and Antaryami, avatars come under Vibhava. Para is the undifferentiated Brahman. Vyuhas are for creation, sustenance and dissolution of the Universe. In Vyuha, there are four expansions: Vasudeva, Sankarshana, Pradyumna and Aniruddha. Vyuha Vasudeva is identical with Para Vasudeva. He has six attributes: Jnana, Aishwarya, Shakti, Bala, Virya and Tejas. From Vyuha Vasudeva is born Vyuha Sankarshana. The principal attributes of Sankarshana are Jnana and Bala, although the other attributes of Vasudeva are present but not in proportion to the Jnana and Bala. You can find reference on Sankarshana in Bhagavatha Purana: https://www.vedabase.com/en/sb/5/25. From Vyuha Sankarshana is born Vyuha Pradyumna. His principal attributes are Aishwarya and Virya. From Vyuha Pradyumna is born Vyuha Aniruddha whose principal attributes are Shakti and Tejas. You can find more information in this blog spot: https://sreenivasaraos.com/category/vishnu/.
I have no idea what different weapons in different hands signify.