Not only will you need the Keratinos Blade and Gauntlet to make the Keratinos weapon, but you will also need to sacrifice one of each to level up your rank with the Necraloid Syndicate
Both items can be purchased from Father in the Necralisk on Deimos using Entrati Standing. The good news is that both items can be purchased at the rank of Neutral, so you don’t even need to rank up with the Entrati to get access to them.
Simply visit Father in the Necralisk to purchase the items from him. Each one will cost 500 Entrati Standing, for a total of 1000 Standing. The best way to earn this standing is to visit Mother and do a bounty for her. This will reward you with Mother Tokens, and you can hand these in to Grandmother for 100 Standing each.
If you plan on sacrificing these items to rank up withe Necraloids, remember that you do not need to build them first, they simply want the blueprints in order for you to successful rank up. If you wish to purchase other items from Father at high levels, you will need to increase your rank with the Entrati to get access to them.
You can also bring certain resources to Father and trade them in for Father Tokens. You can do this under the Parts Requisition option when you interact with him. Father will accept an assortment of Deimos related resources and exchange them for Father Tokens. These Tokens will be needed to continue ranking up with the Necraloid Syndicate. It is a good idea to check in with Father once a day to see what he will to trade for Tokens.