I think you haven't played BG3 in a while.
You can get tons of magic items and tens of thousands of gold (approx 85k by level 4/end EA) in reality for free courtesy of pickpocketing without limitation or risk (when you know the technique and/or can savescum). You have access to a large amount of powerful exploding barrels. Every player can shove huge creatures to their deaths, roll twice on attacks due to guaranteed advantage, dip weapons for +1-4 damage, etc, etc.
Staff of Arcane Blessing is +1-4 attack/save and +2-8 spell attack roll. Something akin to a +5 weapon obtainable at level 2? Seems "balanced" in a way The Spiffing Brit would use the word.
Shattered Flail +2 heals wielder 1-6 hp each time you cause damage. If used in combination with another overpowered item Sapphire Spark that nearly doubles Magic Missile damage, you get healed for each missile. Brokenly OP, especially considering a Magic Missile-build is one of the top burst damage-dealers in 5e even without magic items doubling damage.
Warped Headband of Intellect sets intelligence to 18 and allows quick meta-gaming builds where intelligence can be made a dump stat.
Also, we are comparing level 4 magic item progress in BG3 vs level 8-10 in BG1.
It's a videogame. Of course you can grind, savescum, and exploit the lack of sensible AI behaviour if that's the way you want to play the game.
In numerous EA playthroughs, I've never used dip, only experimented with barrels and shove, not used poison, and actively used movement to height only to get in melee range. If you are not good at DnD combat, using these options might help you, but there isn't really any need to use them.
As for the magic items ( the actual topic of the thread ), while they are numerous, few are particularly worthwhile.
Of the ones you list, the Shattered Flail implementation is completely broken in EA, and would not be particularly OP if correctly implemented as described. The Staff of Arcane Blessing and Sapphire Spark are ambiguously described, so it is less certain what their intended effects actually are, but I think they are both also broken EA implementations, which should be flagged as bugs.
The Warped Headband of Intellect is a hand-placed plot item central to part of the story, which you only get by role-playing specific paths. It's of marginal use; there is always someone in the party who can benfit from better skill roles. If you choose on subsequent playthroughs to deliberately build your character around it, that is your choice; play the game the way you want to.
