Seeing it is secret? - It was because it was secret that they wished to know it. The angel does not say that it was secret, but הוא פלאי hu peli it is Wonderful; the very character that is given to Jesus Christ, Isaiah 9:6 : His name shall be called, פלא Wonderful; and it is supposed by some that the angel gives this as his name, and consequently that he was our blessed Lord.

Why askest.

Judges 13:6 Then the woman came and told her husband, saying, A man of God came to me...

Genesis 32:29 And Jacob asked him, and said, Tell me, I pray you, your name. And he said, Why is it that you do ask after my name?...

secret. or, wonderful. It was because his name was secret that Manoah wishes to know it. But the angel does not say it was secret, but hoo pailee, `it is wonderful;' the very character given to the Messiah: ` His name shall be called pailai. Wonderful,'

Isaiah 9:6 For to us a child is born, to us a son is given: and the government shall be on his shoulder: and his name shall be called Wonderful...

Characters and Names of Messiah
For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace. S uch was the triumphant exultation of the Old Testament Church! Their noblest hopes were founded upon the promise of MESSIAH; their most sublime songs were derived from the prospect of His Advent. By faith, which is the substance of things hoped for, they considered the gracious declarations …
John Newton—Messiah Vol. 1

Judges
For the understanding of the early history and religion of Israel, the book of Judges, which covers the period from the death of Joshua to the beginning of the struggle with the Philistines, is of inestimable importance; and it is very fortunate that the elements contributed by the later editors are so easily separated from the ancient stories whose moral they seek to point. That moral is most elaborately stated in ii. 6-iii. 6, which is a sort of programme or preface to iii. 7-xvi. 31, which constitutes …
John Edgar McFadyen—Introduction to the Old Testament