kname

Cancel is just such a horrible counter that I refuse to use it on principle. Essence scatter will counter most things that need it and is cheap enough to actually get some use.

This deck is actually designed as a starter deck for a high school club so I don't think sideboards will be used. That does remind me that I really should have at least some counterspells in an introductory blue deck though.

It probably needs more auras if you intend to 1-hit people consistently.

The cantrip is worth the defender, especially when you can sac or bounce it whenever you want since you can tutor with overlord.

I personally prefer the GW or BW version, but this looks solid.

No dormant sliver?

Then put in Fencing Ace because you need more creatures.

First, it needs more creatures, probably 3-4 sunspear shikari, or you could go for signal pests since you will be spreading out your equipments and it helps with metalcraft. Replace cranial plating with golem-skin gauntlets because of the price. sword of vengeance isn't important, and no-dachi is useless. O-naginata is risky, and should proabably go too. I recommend replacing these equipment with bonesplitter and silver-inlaid dagger for damage buffs on your fist/double strikers, bone saw for boosting metalcraft and being free with the steelshaper, and kitesail for more evasion.

The lifestaff really doesn't give enough life to be worth the extra cost over shuko and bone saw, especially because in my meta, most of them have little to no removal. I prefer the trample over the flying because my enough of my creatures already have flying.
The thing about bonesplitter compared to shuko is that the free equip is incredibly useful in pumping my kor while still putting more of them on the field. it smooths the process of playing creatures while also putting the equipment on them.

The outfitter isn't to make say, argentum armor less to equip, its more to put a kor out while also sticking one of my equipment onto the duelist or armament master. The skyfisher is a great flier in this kind of deck, since it is essentially a 1-drop if i top deck it so i can equip more the turn it comes out, it is an evasive kor so with an amament master it hits consistently for 4+ each turn, and it synergizes well with bone saw and new benalia.

most of those cards are more expensive than i would like for this deck, but there are a few with different reasons for me to not use them:
The life staff doesn't do enough because i rarely want to trade, and it doesnt really discourage a doom blade
bone splitter and leonin scimitar are less efficient for what i want them to do than shuko and bone saw, since the toughness boost doesn't matter much, and bone splitter costs more to use.
darksteel citidel is bad when most of my creatures cost ww and i dont need it for the metalcraft that are more expensive than i want and/or not a kor.
the trample is a good idea, since i often find my duelist unable to get through, so ill add 3 vorrac battlehorns.

Yeah I can't believe I spaced the library.

seems really vulnerable to removal, but is still an interesting deck

as a last thought, you may want to drop an island for a plains, but i can't say that for sure

the way the sideboard runs is replacing the ethereal armors with azorius charm against aggro, acolytes reward replaces bioshift against RG monsters, and glimpse and hidden strings instead of ethereal armor, ephara's enlightenment and a bioshift if they sideboard something.

you can lose the ordeals and replace them with another bioshift and ephara's enlightenment

for sideboard, replace the gridlocks with glimpse the sun gods, brave with acolytes reward

edit: replace the celestial flares with azorius charm

and add three ethereal armors instead

enlightenment not plenty

then add either the scrys or gates

lose the lawmages and eidolons, and add one each of battlewise, cavalry pegasus, phalanx leader, and gods willing. then drop your triton tactics and oredeals for a fourth bioshift and three ephara's enlightenments