In the SeedHarvestComponent there are a couple of spots you modify to adjust the collection values and damage types.
Harvest Resource Entries
Expand Entry 0 which is for fiber If you want the sickle to collect other resources just expand the various sections to see what seed component it is and follow the same steps below.
The 4 sections you need to modify are at the bottom of Entry 0
Damage Type Entry values Overrides - Duplicate the DmgType_melee_dino_Herbivore and change entry 0 to your DmgType_Sickle.
Damage Type Entry Weight Overrides - This sets how well the dmgtype collects the resource and corresponds with the Damage Type entry value overrides above. This is usually set to Decimals from what i have seen 0.2 to 0.6 or sometimes lower. If you plan on having different tiers of sickle stone/metal you can set the rate to make collection better with one than the other. The higher the number the better it is at collection. Create a new element and set it to 1.0 and then just adjust it to get the number you like.
I am not 100% sure what the next two entries do maybe someone else has a better idea but I found that it is usually set to 1.0 or 2.0 I havent had much time to experiment with these settings.
Damage Type Entry Min Quantity Overrides - leave blank or try setting to 1.0
Damage Type Entry Max Quantity Overrides - Same Leave blank or set to 1.0
After that you can set your Damage Type in the Harvest Damage Type Entries below the Harvest Resource Entries from there you can just duplicate one of the entries and set the Damage Type Parent to your DmgType_Sickle. Then adjust your Damage Multiplier.
after your modifications are complete the new SeedHarvestComponent has to be referenced in the Primal_Game_Data_BP. Search for Remap Resource Components and add a new entry.
From Class - SeedHarvestComponent
To Class - SeedHarvestComponent_child
You should be all set after that 