how to use weapons

If I use a mixture of 3 fairy swords of fire element (from the platinum trial shop) and 2 elemental swords of fire element (from completing the domain of trial) or vice versa, will the damage output be equivalent to 5 fairy/elemental swords of fire element? And will the cumulative effect description of high-level weapons interact with other weapons as long as they are of the same element (for example, 5 grass swords but different levels and sources)? I am planning to attack Goddess difficulty levels in Realm of God but I am having difficulty because the Goddesses' stats are too high (1 respawn when watching an ad is not enough for me to kill the boss, and if I respawn more times, the ruby ​​cost is too high). Currently I am using a mixture of 5 swords of all 5 elements to optimize resources before using a pure 1 element combo. My senia level is 92 and all swords are level 90 and above.