I read project readme, checked client side and server side configurations, and no such feature exists - I believe so

Is your feature request related to a problem? Please describe.
Somewhat, Blood Magic atoments can be applied to specific things like weapons by holding it in offhand and using INTERACT to apply it. Dosent work with duel-handed property weapons likey due to offhand being disabled whilst holding the weapon

Describe the solution you'd like
considering this might not be the only niche case for this kind of problem, having a "offhand interaction exception" option in the config that would allow whitelisted items to have a simulated Interact (right-click) input to use them would be nice. Though, to keep some 'balance' the interaction exception only would work if you are not actively swinging the weapon like how shileds with singel-hand weapons don't activate until you are finished swinging the weapon

Describe alternatives you've considered
making a datapack or script to allow this interaction via crafting, but it would be a bit of a pain to implement

Additional context
this overide would allow the offhand item slot to render BUT no offhand item is seen in the offhand

Interestingly enough, this also extends to corail tombstone's tome mechanics as some actions require the tome to be in the main hand while the item you are using it on is in the offhand, making double-hand items unable to be used

@Shibva Special books in Corail Tombstone are in offhand to interact a decorative grave.
The mainhand item is used for the item to use the book on and there's a curios book slot to avoid to have the book in offhand.

"Two-Handed" behaviour works exactly as intended.

This issue is a matter of invalid configuration. If there is a weapon which requires an off hand item to work together with, the correct solution is to not mark is two handed.
This can achieved by assigning a different weapon preset to the weapon.

Weapon presets available:
https://github.com/ZsoltMolnarrr/BetterCombat/tree/1.21.1/common/src/main/resources/data/bettercombat/weapon_attributes

Custom weapon preset can be also made.

@ZsoltMolnarrr I agree, but the problem is that because of how it's coded, I cannot apply/use something to put on the weapon due use being fully canceled.

For example; a mod makes it to where you can coat your weapon with a potion to apply it on hit; but in order for it to be applied, you need to use the item in the offhand while holding the weapon in the main hand.

This is what I mean, weapons where this would be comparable end up being incomparable due to the restriction preventing it from triggering it

This is the case with something in blood magic where tools and weapons can gain properties for a set number of uses but can only be applied if you use it in your offhand with the tool/weapon you wish to apply it on.

Heres a visual. all actions im doing are right click/use key