Who spoke to Manoach and his wife? An angel or prophet?

The pasuk indicates that he was a malach:

ב  וַיְהִי אִישׁ אֶחָד מִצָּרְעָה מִמִּשְׁפַּחַת הַדָּנִי, וּשְׁמוֹ מָנוֹחַ; וְאִשְׁתּוֹ עֲקָרָה, וְלֹא יָלָדָה.	2 And there was a certain man of Zorah, of the family of the Danites, whose name was Manoah; and his wife was barren, and bore not.
ג  וַיֵּרָא מַלְאַךְ-ה, אֶל-הָאִשָּׁה; וַיֹּאמֶר אֵלֶיהָ, הִנֵּה-נָא אַתְּ-עֲקָרָה וְלֹא יָלַדְתְּ, וְהָרִית, וְיָלַדְתְּ בֵּן.	3 And the angel of the LORD appeared unto the woman, and said unto her: 'Behold now, thou art barr

but malach can mean either angel or prophet. Thus, consider the following pasuk from the beginning of Chagai:

יג  וַיֹּאמֶר חַגַּי מַלְאַךְ ה, בְּמַלְאֲכוּת ה--לָעָם לֵאמֹר:  אֲנִי אִתְּכֶם, נְאֻם-יְהוָה.

13 Then spoke Haggai the LORD'S messenger in the LORD'S message unto the people, saying: 'I am with you, saith the LORD.'

Other pesukim seem to indicate this as well. Thus, for example, earlier in sefer Shofetim, Hashem sends a navi to the people:

ז  וַיְהִי, כִּי-זָעֲקוּ בְנֵי-יִשְׂרָאֵל אֶל-ה, עַל, אֹדוֹת מִדְיָן.	7 And it came to pass, when the children of Israel cried unto the LORD because of Midian,
ח  וַיִּשְׁלַח ה אִישׁ נָבִיא, אֶל-בְּנֵי יִשְׂרָאֵל; וַיֹּאמֶר לָהֶם כֹּה-אָמַר ה אֱלֹהֵי יִשְׂרָאֵל, אָנֹכִי הֶעֱלֵיתִי אֶתְכֶם מִמִּצְרַיִם, וָאֹצִיא אֶתְכֶם, מִבֵּית עֲבָדִים.	8 that the LORD sent a prophet unto the children of Israel; and he said unto them: 'Thus saith the LORD, the God of Israel: I brought you up from Egypt, and brought you forth out of the house of bondage;

and immediately after that a malach Hashem appears to Gideon:

יא  וַיָּבֹא מַלְאַךְ ה, וַיֵּשֶׁב תַּחַת הָאֵלָה אֲשֶׁר בְּעָפְרָה, אֲשֶׁר לְיוֹאָשׁ, אֲבִי הָעֶזְרִי; וְגִדְעוֹן בְּנוֹ, חֹבֵט חִטִּים בַּגַּת, לְהָנִיס, מִפְּנֵי מִדְיָן.

11 And the angel of the LORD came, and sat under the terebinth which was in Ophrah, that belonged unto Joash the Abiezrite; and his son Gideon was beating out wheat in the winepress, to hide it from the Midianites.

Ralbag there says that this "malach" was the navi, I believe specifically Pinchas, and interprets the rest of the narrative there in like manner. He does the same thing to the malach Hashem in the incident of Manoach and his wife being informed that she is to give birth. His reasoning is that both Manoach and his wife see the malach, and if it were prophecy to them, they would not have a shared vision. Therefore it must have been a human. Of course, the ascendence of the malach in the flame at the end is going to be more surprising, but Ralbag says the navi did this for effect.

Thus, he writes:

Behold, this malach who spoke to Manoach and to his wife was certainly a prophet, for it is not of the way of prophecy that it addresses two in this manner mentioned in this place. And behold, I think that this prophet was Pinechas. And behold, he did not wish to eat of the goat kid, just as he did not wish to eat of the meat and matzot which Gideon brought before him, so that it would settle more in the hearts of Manoach and his wife that he was a malach Hashem {does he mean agent here, or tricking them that he is an angel? probably the former, but see below}, so that they would be careful of all that he said to them. And behold, the malach {=navi} ascended in the glame of the alter, just as the matter was in that which he did to Gideon, in the matter of the fire that consumed the meat and the matzot, and he went {=disappeared} from before his eyes, then he knew that it was a malach Hashem. {To clarify, see Shofetim 6:21-22, וּמַלְאַךְ ה, הָלַךְ מֵעֵינָיו | וַיַּרְא גִּדְעוֹן, כִּי-מַלְאַךְ ה הוּא.} For this reason, the prophet did not wish to reveal his name

{That is, in Shofetim 13,

יז  וַיֹּאמֶר מָנוֹחַ אֶל-מַלְאַךְה, מִי שְׁמֶךָ:  כִּי-יָבֹא דבריך (דְבָרְךָ), וְכִבַּדְנוּךָ.	17 And Manoah said unto the angel of the LORD: 'What is thy name, that when thy words come to pass we may do thee honour?'
יח  וַיֹּאמֶר לוֹ מַלְאַךְ ה, לָמָּה זֶּה תִּשְׁאַל לִשְׁמִי--וְהוּא-פֶלִאי.  {פ}	18 And the angel of the LORD said unto him: 'Wherefore askest thou after my name, seeing it is hidden?' {P}

}

for then, they would not believe very much in prophets, for the word of Hashem was rare then. {Is this saying that he was pretending to be an angel?? No.} And in order to increase their faith in his words, he concealed from them who he was. And behold, Manoach and his wife were fearful of death for the same reason that we mentioned in this matter by Gideon.

Here (at the of page 108 and the beginning of page 109), Ralbag discussed why Gideon thought he would die. Because that which he saw was very spiritual, "he thought that he had already seen the metziut haruchanit, and it was already well-known that when this happens, death comes after it."

I am not so sure I agree with Ralbag that it must have been a prophet rather than an angel. This reading, though, changes the nature and feeling of many incidents recorded in Tanach, so it is something to consider; and it is also a good possibility.