What does Reginald mean?
From Germanic 'ragin' ('counsel, advice') + 'wald' ('rule, power'), i.e. 'ruler by counsel' / 'counsel-power'. Note: this is 'ruler/power', NOT literally 'king'. Reynold and Ronald are closely related forms.
What does Herman mean?
From Germanic 'heri' (army) and 'man' (man), giving 'man of the army, soldier'. The Latinized Arminius refers to the same Cheruscan war-leader.