I have always been scared of you, With your Luftwaffe, your gobbledygoo.
Now the speaker switches back from describing herself as a victim to addressing her father, saying that she's always been scared of him.
Then she goes on to describe her father's German characteristics. "Luftwaffe" is the German word for air force, and is specifically used to refer to the German air force of World War II.
"Gobbledygoo" follows "Luftwaffe," masked as something of significance, but it's actually a nonsense word. Yet it probably refers to the strangeness of the German language to an English-speaking listener.
And your neat mustache And your Aryan eye, bright blue.
The "neat mustache" and blue "Aryan eye" describe the father physically, and make him seem very German.
The mustache aligns her father with Hitler, whose toothbrush-shaped mustache was emblematic.
"Aryan" is a term that, during the Nazi rise to power, referred to Hitler's "perfect race" of blond and blue-eyed people who were seen as "superior" to Jews and gypsies.
So the speaker's father is now like the German image of terrible perfection – with Hitler's mustache and idealized bright blue eyes.
Panzer-man, panzer-man, O You –
"Panzer-man" refers to German tank drivers, and continues the image of the speaker's father as scary and terrible.
Then, again, we get the phrase "O You," but this time it's in English. The poem has gone a long way since we heard the "Ach, du" (line 15). This "O you" follows not a prayer to recover him, but an invocation of his horrors.