How do you resolve the damage and effects of Eldritch Claw Tattoo’s “Eldritch Maul” ability on a hit that is beyond your weapon’s normal melee range?

The Eldritch Maul ability says:

each of your melee attacks with a weapon or an unarmed strike can reach a target up to 15 feet away from you, as inky tendrils launch toward the target. In addition, your melee attacks deal an extra 1d6 force damage on a hit.

So, let’s say that I’m using the Eldritch Maul ability with a normal shortsword to melee attack a target that is 15 feet away. Is it only the inky tendrils that hit the target, dealing just 1d6 force damage, or should I also factor in the 1d6+STR/DEX piercing damage of the shortsword as if it hit the target as well?

Follow-up question: If the weapon was magical, would its magical properties factor into the attack?

For example: Would your attack with the Eldritch Maul ability benefit from a +1 weapon?

In another example: Would a Dagger of Venom’s poison property proc on a melee hit from 15 feet away while using the Eldritch Maul ability?

Dagger of Venom says:

You can use an action to cause thick, black poison to coat the blade. The poison remains for 1 minute or until an attack using this weapon hits a creature.