Sarcasm is a taunting statement that usually says one thing while meaning the opposite. It aims to ridicule or bitterly criticize the object. Here, it appears in the B stanza ("Where is now your arrogance..."). By asking about arrogance, awesome deeds, valor and victories, the speaker actually denies all of those in a very deprecating way.
Bob and wheel is a rhythmical device made famous by the poem "Sir Gawain and the Green Knight". It consists of two lines: the first one is extremely short (usually two syllables), and it's called "bob"; the second is longer and may have an internal rhyme. Here, the D stanza uses this device: "must be" is bob, and the following line is the wheel.
Allusion is a reference to a famous person or event, usually from mythology or history, or classical literature. Here, the C stanza employs a lot of allusions to Biblical figures of Adam, Solomon, Samson, Delilah, David, Bathsheba. Allusions are never explained, as the writer presumes that the reader is already familiar with them.
Simile is a figure of speech that compares one person, thing, or phenomenon to another, with or without conjunctions such as "as" or "like". It usually compares particular to abstract and vice versa. Here, the A stanza employs a simile ("Oblique, like a baldric").
