Wikipedia says a foreign minister is often regarded as the most senior ministerial position below that of the head of government (prime minister or president); it is often granted to the deputy prime minister in coalition governments.
In the US, their Foreign Minister (Secretary of State) ranks ahead of all other Ministers in authority and precedence with Thomas Jefferson having been that nation’s first Secretary.
In the UK the Foreign Secretary is one of the four great offices of state.
In Australia it is ranked 5th after PM, Deputy PM, Treasurer and Defence.
In Canada the Foreign Minister is ranked on the front bench.
In Ireland the Foreign Minister is ranked fourth. Likewise fourth in France. In Germany it is ranked second.
In NZ The Foreign Minister is ranked No 28 and is not even in the Cabinet.
The point is that in basically every country in the world, this is one of the great offices of state. I don’t have a problem with Peters being Foreign Minister as much as with the decision to have it outside Cabinet. That is a strategically stupid decision.