The secret grip has yet to be readded, The formula for the sword pedestal doesn't require it. There's a specific handle from the ones you can buy, a specific grip from the ones you can buy, and a specific sword which may or may not be the one you think it would be, that work as the combination for the formula.
If you want to figure it out yourself. This is all the info.
If you want spoilers, snoop around posts... there's spoilers here and there.