Frustrated by the contrasting views expressed here

[Voltaire2]

11. It doesn't violate the constitution but it is an impeachable offense.

The constitutional power is not constrained by what the crime was (1), and any pardon would fit under (2) so that doesn't make sense, and "what a typical pardon" (3) is, is irrelevant to its constitutionality, nor does "Arpaio hasn't even been sentenced" matter (3 again,) see Ford's pardon of the uncharged Nixon.

"and he shall have Power to grant Reprieves and Pardons for Offenses against the United States, except in Cases of Impeachment." - that is the entire text that gives the president the pardon power. The only limits are "offenses against the United States" which limits this to federal charges, and "except in Cases of Impeachment".

He violated ethical norms, but not the constitution.