"Shower-door water-deflector eroded, came off"

What's it made of? Not obvious to me:

(Shower door, etc, was installed in perhaps 1940, maybe a few years
earlier)

.. Aluminum? Doesn't have that "aluminum feel", seems not lightweight
enough for that.

.. Some other alloy?

Anyway, it seems to be made of *some* fairly-lightweight metal.

(Poteltial clue?: Although it shows no aluminum-like wee surface-pits,
2 of its 4 screw-holes (all are near the top edge) have been eaten
away, in a V-shape gap, out to edge of the piece. (The wide part of
the V being at the edge, narrow part being the wee-hole itself),

QUESTION: What to do to reattach this thing to the bottom of the
shower door?

Drill new holes both through the deflector-piece and into the door

(Inner question: what kind of metal-screws will grip the
newly-drille *no-threads* hole?)

Quick and easy, via some kind of waterproof glue (epoxy, perhaps?)

Other ideas?