so lets call the item AwesomeSword
So in the items.xml file, you should add an entry to include AwesomeSword into the code and give it a custom tag (in this case, perkSwordCrafting)
<item name="meleeWpnSwordT3AwesomeSword">
<property name="Tags" value="machete,melee,grunting,light,longShaft,perkFlurryOfBlows,weapon,meleeWeapon,attAgility,perkDeepCuts,perkTheHuntsman,canHaveCosmetic,perkSwordCrafting"/>
.....
</item>
In the recipes.xml file, add it with the custom tag
<recipe name="meleeWpnSwordT3AwesomeSword" count="1" craft_area="workbench" craft_time="60" tags="learnable,perkDeepCuts,perkSwordCrafting">
<ingredient name="meleeWpnBladeT3MacheteParts" count="5"/>
<ingredient name="resourceForgedSteel" count="10"/>
<ingredient name="resourceWood" count="10"/>
<ingredient name="resourceLeather" count="3"/>
<ingredient name="resourceDuctTape" count="3"/>
<effect_group>
<passive_effect name="CraftingIngredientCount" level="2,6" operation="perc_add" value=".5,2.5" tags="meleeWpnBladeT3MacheteParts,resourceForgedSteel,resourceWood,resourceLeather,resourceDuctTape"/>
</effect_group>
</recipe>
Then add the new crafting tier into one of the existing perks (for this example, into deep cuts):
<insertAfter xpath="//perk[@name='perkDeepCuts']/effect_group/passive_effect[@name='CraftingTier']">
<passive_effect name="CraftingTier" operation="base_add" level="0,5" value="5" tags="perkSwordCrafting"/>
</insertAfter>
You should now be able to craft a Q6 Awesome Sword at perk level 0 once you unlock the recipe.
Note, I left perkDeepCuts on the example if you want to tie in the benefits of the DeepCuts perk into the weapon The game will see both crafting tiers (so it will go from 6 to 11) but should only craft at Q6 max. I believe it hard limits it to a max level of Q6 if the item is setup to only go to a max level of 6. I believe I created a situation where the crafting tier level was 7, but I could not craft at that level
Another option is to create a brand new perk that ties directly to it and remove perkDeepCuts altogether.