Magic items can be very impactful but they also risk the sinking of a substantial amount of gems and effort into an inconsequential effect so it's important to pick and choose. They compete for gems with rituals and empowers and to my mind, at least in the early game, generally win. I'd rather make a magic item than summon a handful of monsters.
Shroud of the Battle Saint (S), Prot 9 (body), unit is always Sacred and Blessed. Depending on how you designed your god this is way more powerful as a buff than a simple Ring of Regeneration which might be the equivalent of one of your blessings. The Shroud gives all of them passively. If your commander is already Sacred then Flask of Holy Water (W) does just as well.
Construction Level 0 stand outs:
For me it's the resistance rings, particularly the poison resistance ring which for some reason does double and gives poison touch too. Once you know who you're fighting it can be very powerful to buff your commanders against them.
Construction Level 2
The magic factory you have probably assembled in your capital can be considerably enhanced at this level.
Dwarven Hammer (EEE) reduces gems used in making magic items by 2. It costs 15 so it doesn't pay for itself until the 8th magic item so you want a couple of guys who craft all the time rather than having everyone on research and then suddenly 7 of them craft an item whenever you roll a new thug.
Owl Quill (A) +6 research. Make one for all your researchers. With some civs this will almost double your research production.
Halberd of Might (E) may be the most powerful weapon stats wise and it has reach so you'll repel a lot of attacks. Other weapons may have fancy effects but this is normally going to be better unless you need an AOE weapon.
Ice Mist Scimitar (AW) decent weapon with AOE exhaustion and +10 resist cold. Well worth considering against Water/Cold races.
Mace of Eruption (FF), Thunder Whip (A) the only Construction 2 AOE damage weapons.
Gloves of the Gladiator (NN) but who needs AOE when you can get 4 attacks?
Boots of the Behemoth (E), Boots of Giant Strength (E). Earth gives the only good lowbie boots. Trample is really powerful if your champion is big (eg Dai Oni) and is fighting lots of weak troops.
Dragon Helm (F) really nice collection of bonuses including great protection and a small morale buff.
Bracers of Protections (E) extra protection and defence for a very cheap price.
Handful of Acorns (E) this is great in a Death Match because 3 little shrublings will really waste the other commander's time and resources. If he hits one of these he's not hitting you. Considerably improves your commander's chance to win.
Construction Level 4
Some decent AOE weapons: Frost Brand (W), Snake Bladder Stick (N)
Various skill booster items which are significant because they unlock items you couldn't make before. Thistle Mace (NN), Skull Staff (DD), Armour of Twisting Thorns (NNBBB), Earth Boots (EE), Flame Helmet (FFFF), Winged Helmet (AAAA), Bag of Winds (AAAAA), Blood Stone (EEBBB), Brazen Vessel (BBBBB), Crystal Coin (EESS), Water Lens (W)
Herald Lance (SS) at last, a good weapon for a general or use Whip of Command (N) if you're leading slaves.
Wand of Wild Fire (FFF) good weapon for a mage, chucks Fireballs, a great AOE spell.
Skull Standard (DNN) is a great aoe fear and panic weapon for a general or his/her support.
Wraith Sword (DD) is our first lifestealing weapon.
Elemental Armour (FEE) is a great suit of plate for commanders who don't need to use Shrouds.
Crown of Command (SS) and Helmet of Heroes (FE) are both great hats for generals
Spirit Mask (DDN) is an absolutely fantastic hat for a Deathmatch duellist.
Amulet of Giants (N) is a combo item with the trample boots or defence against tramplers like Elephants.
Bane Venom Charm (DD) unlocks a behind the lines attritional strategy. It's best with Summon Shade as the shades are immune to the disease. It's not very obvious how impactful it is but it wouldn't take much to do more than the cost of a shade plus this plus a cheap +stealth bonus item. More potent later in the game or against higher difficulty AIs.
Cornucopia (NNN) 2 temporary Nature gems and +50 supply make this a very powerful item for your main armies once you've unlocked strong Nature magic like Haste (Ench 4).
Horn of Valour (N) +1 inspirational leadership. Nothing fancy, but might swing close battles.
Sanguine Dowsing Rod (B) improves Blood hunts. Gotta catch em all!
Skull Mentor (DD) +14 Research, will stack with the Owl Quills if you're both Death and Air, makes a perfectly adequate alternative if not. The cost of 10 gems each and harder prereqs make it worse than the Owl Quill.
Charcoal Shield (FF), Vine Shield (NN) punish attackers, making these shields great for thugs.
Now a few general points:
- it's usually better to make a 2H weapon rather than a 1H weapon and shield. Less crafter time less gems for the set. There can be exceptions if you particularly want a certain set or if cost is no object for this particular commander.
- basic Thug gear is Shroud (or Flask of Holy Water) plus Halberd of Might. You can give them more stuff but they will do 90% of the job with just those two items and it might be better to make more Thugs than to overload one.
- next items to give Thugs in most circumstances are the Boots of the Behemoth and Amulet of Giants.
- Astral items get a bonus because of the way Alchemy works. If I run out of Astral gems I can alchemise any gems I don't need at 2 for 1. If I need Fire gems and I have surplus Earth or Water gems I turn them into Fire gems at a rate of 4 for 1.
- Many commanders start with items. When considering giving a commander a new magic armour, helm, shield or weapons check what mundane armour they're already wearing.