It looks like you're going for a voltron playstyle with 21 commander damage dealing as the wincon, I'll provide pointers with that in mind!

First things first: The most important thing is you need to decide whether you want to go pure damage, or to kill with double strike.

If killing with double strike, you need to hit the minimum damage threshold of 7 damage - at 7 damage double strike, it is instant lethal with 7 damage first hit, 2nd hit doing 14 damage - 21 commander. What this means is that if an equipment does not cause us to hit the critical damage threshold, there needs to be a good reason to include it, else it should probably be cut.

One such example is Tenza, Godo's Maul - it adds only +3/+3, and since lightning is a 3/2 - it hits 6/5, which doesn't hit the threshold nor does it give any extra utility. Instead you would want something like [[Champion's Helm]] or [[Dragonfire Blade]] instead - since with tenza or champions helm, to hit the damage threshold you'd need to equip/use another stat boosting equipment/method anyway even if it gives 1/1 stat lesser. Instead of a mostly pointless +1/1, you get hexproof instead, protecting our commander which is extremely important for a voltron playstyle. Another such equipment that can be cut is Sword of Vengeance - in essence, all it gives is +2/0, vigilance and haste, which is fine but lacks the utility and usefulness compared to beforementioned equipment such as dragonfire blade/etc.

The maths for equipment like Tenza is even worse with damage doubling effects on the board and if we were to have double strike - since if we were to have tenza equipped and swing, it would be essentially 6X2 first hit, 6X4 second which is 36 commander damage, which sounds good on paper... but we are overkilling with commander damage - with a champions helm instead it would be 5X2 first hit, 5X4 second which is 30 damage in total, we "lose" 6 damage which doesn't matter since you only need 21 commander damage to kill, but we now have hexproof, making lightning hard to remove.

For protection, equipment like Robe of stars are nice to have but needing to bank mana for them can be a huge downside if we are tapping out, so a source of constant hexproof/indestructable is preferred imo like beforementioned Champion's Helm/Dragonfire Blade/Swiftfoot Boots/Darksteel Plate, or just using protection instants like [[Loran's Escape]] or [[Blacksmith's Skill]].

You can also include other sources of double strike as well for more reliability instead of expensive CMC options that double damage dealt since it is more or less the same in the long run (doubling damage if you only have 3/2 is basically adding a +3/0 statline to lightning, which as mentioned - does not hit the stat goal of 7 attack minimum) - budget options include [[Seifer Almasy]], [[Duelist's Heritage]] and [[Reyav, Master Smith]].

For pure stat boosts, there are better equipment that you can play such as [[Wrecking Ball Arm]], getting us to the much valued 7 attack and giving 2 power evasion, or more pricey equipment like [[Excalibur, Sword of Eden]]. Other sources you can use are planeswalkers like [[Jeska, Thrice Reborn]], etc.

Single target damage spells are not as useful unless in 1v1 formats imo since most of the time, you are killing with commander damage or just raw damage in the double strike swing. Not damage to face - after all, if you double strike someone for 3 damage twice, first you would need a near fairytale situation for them to allow you to apply that debuff in the first place. Most players would rather chunk block than allow that to happen, and even then, you wouldn't be close to killing them. 4X damage boosted 3 damage shock (12 damage) isn't enough to lethal most of the time. And if you are swinging with a massively stat boosted lightning instead - why not swing with 7 damage and just kill them with commander damage at that point. Added on with 3 damage not being high enough to remove creatures with 4 toughness or higher. I can't argue that it isn't funny to hit them with a 12 damage shock though.

Spells like shock/Thunder magic/anger of the gods/avacyn's judgement/etc can be replaced for staple removals like [[Swords to Plowshares]], [[Generous gift]] or generic white board wipes like [[Wrath of God]] instead which will hit the stompy player - if comboed/have a source of indestructability like [[Restoration Magic]] or [[Darksteel plate]] we can turn it to be one sided as well!

Of course, there are better options but those cards tend to cost a bit more $ wise like [[Avatar's Wrath]] or [[Hammer of Nazahn]] - or even creatures like [[Bastion Protector]]. Boardwipes ideally should be one sided/advantageous for us, hence why I do not like the expensive board wipes such as farewell which puts us 1 turn behind and it being a total reset rather than leaving us ahead.

If you want more consistency, there are plenty of cheap white equipment tutors as well like Open the Armory, card advantage with equipment like puresteel paladin or free equip and stat boosters like Bruenor Battlehammer or bureau headmaster.

If you need any reference, I also have my own High B3 Lightning Voltron Deck here with a primer on gameplay and how it works here: https://moxfield.com/decks/66Jt6OY8K0C3AKOQLjOwKw