Erelim: Tearful Angels, Jewish Valkyries
[Israels klage und hoffnung Ps. 22, Die Bucher der Bibel, by E.M. Lilien]
Behold the valiant [erelam] shall cry out, the angels of peace shall weep bitterly.
While there may be a progressive parallelism intended here, i.e., "both mortals and divine beings weep," esoteric readers of this verse draw a straight parallel between the erelam and the "angels of peace" -- the verse refers to two types of angels.
Maimonides lists erelim among the ten classes of angels (Hilchot Yesodei ha-Torah 2:7). They are ascribed a number of overlapping functions in different sources.
They seem to be closely tied to moments of death and destruction. Thus Hagigah 5b reiterates the Isaiah passage regarding the destruction of the Temple, while Jewish mystics make them witnesses to the humiliation of the Shekhinah (Zohar I:182a; also see Lamentations Rabbah Proem 24 and 1:23)
Erelim apparently have the responsibility to retrieve the souls of the righteous dead. Thus in the account of the death of Rabbi Judah ha-Nasi, during which the Sages attempted to keep him alive via continuous prayer, a disciple finally admits defeat by saying, "Both the erelim and the mortals held on to the Holy Ark [Rabbi Judah]; but the angels overpowered the mortals, and the Holy Ark has been captured" (Ketubot 104a) [notice the militaristic turn of phrase, an allusion to the capture of the Ark of the Covenant by the Philistines in I Samuel. Since erelim are linked to war and destruction elsewhere, perhaps there is a Valkyrie-like element to them]
They also have a strong predisposition to cry; in Genesis Rabbah 56:6, it is the Erelim that weep over the thought that Abraham will go through with the divine instruction to kill his son. They personify divine pathos.
Paradoxically, given what appears above, they are also associated with life. In Midrash Konen, they are the angels described as the genius of foliage, impelling plant growth (2:25).
Zal g'mor - to learn more, read the Encyclopedia of Jewish Myth, Magic, and Mysticism: http://www.amazon.com/Encyclopedia-Jewish-Myth-Magic-Mysticism/dp/0738709050