[cm/sign/] with Ed25519-BLAKE2b with Merkle-tree hashing.
[cm/pub/ed25519-blake2b] public keys are used.

It is similar to [cm/sign/ed25519-blake2b], but
HashEdDSA mode is used with [cm/hash/blake2b-merkle] hashing.

"ed25519ph-blake2b-merkle" algorithm identifier is used in signature.