Originally Posted by
RogueJK
Artificer is typically a better choice for a 1 level dip at the start for a caster to gain CON save proficiency. You still get Light Armor, Medium Armor, and Shield proficiency, but it doesn't slow down your spell slot progression due to the special half-caster calculations used by the Artificer class (gaining a spell level on odd numbered levels instead of even like other half-casters), and you get access to a couple additional cantrips along with a couple 1st level spells known from a spell list that's a blend of divine/nature/arcane magic so there's bound to be some options that wouldn't otherwise be available to you.
Thus, unless you're specifically planning to take Fighter 2 at some point to gain Action Surge, or you really need the fighting style or martial weapon proficiency for a gish build, Artificer 1 is typically a better choice than Fighter 1 on a spellcaster.
This is especially true for most Wizards that want armor/shield proficiency, since both Artificer and Wizard are INT-based casters.
However, I don't think dipping anything for CON save proficiency is worth it on a Bladesinger specifically, since they don't need the armor/shield proficiency, plus their access to Extra Attack is delayed to Level 6 anyway, and you don't really want to further delay it to Level 7. Most importantly, they already get +INT to Concentration checks while Bladesinging, which will apply to most serious fights. You definitely don't need both Warcaster AND CON proficiency (via dip or Resilient) on a Bladesinger.