Is "gains Secrecy 1" additive or does it replace the value of cards that already have Secrecy?

e.g. does O Elbereth! Gilthonial! become Secrecy 1 or Secrecy 5 when it is the first event card played by a Spirit hero wearing a Leaf Brooch.

Pretty confident it is additive. This is consistent with other rulings like Surge and Archery being additive. Although, I am not sure if we have received a ruling specifically for Secrecy.

Well, the definition itself looks additive: "reduce the cost by X."

if there is two reductions, then it can be added.

Surge is not followed by a number, so surge + surge doesn't give surge 2, but simply surge followed by another surge.

Thanks.

Looking at the deck I put together, O Elbereth is the only card it would effect anyway.

Have had very good times repeatedly playing Elven Light & Swift and Silent for 0 cost in recent games due to some good early Brooch draws. I don't know why Secrecy is so looked down on

Another card that falls under my original question would be Out Of Sight (Cost 5 Secrecy 3) from The Long Dark (which I don't own). At Secrecy 4 it becomes a very good card indeed.