Burgundians:

• Economic upgrades are available one Age earlier than other civs

Besides a very solid FC possibility and a super early Double-bit Axe Build-Order, it has long lasting effect, basically you get an Chinese/Celts Dark Age Eco. Wheelbarrow isn't worth it before 30+ vills anyways.At first it sounds revolutionary, practically it needs a buff to keep up with other Eco bonuses, but considering they have another Eco bonus....

• Fallen Knights return 50% of their gold cost

The second Eco bonus, while the other one is strictly relevant to Dark Age and Feudal Wars, this one is roughly equal to Berber's Eco bonus, heavy Cavalry discount. Since Cavalry are less likely to mass into a deathball, unlike Archers, you can almost consider a Burgundy Knight 37g.

Burgundians will most likely have Handcan, Cannons, no Arbalest, Nor Heavy CA, we're going to get a second version of Franks, with kinky exotic Unique Teches that acts like a panic button, doomsday savior.

• Coustillier: Cavalry unit that can charge their attack stat

Unlike Franks they have a solution for a CA and other micro-intense fast units that abuse Knights.

Just like Magyar were an uninspired version of Huns, here we get Franks 2.0.

Sicilians:

• Castles and Town Centers are constructed 100% faster

Relevant pretty much only at Castle Dropping, sadly on the new overly open Arabia it almost never happen at high levels, so kinda mediocre niche.

• Land military units absorb 33% of all incoming bonus damage

Mathematically not too significant at Feudal Age:Scount takes 4 hits instead of 3 from a SpearArcher takes 7.5 hits instead of 6 from a SkirmNot impressive. However, can defintely justify an early Scouts Rush.

Same about every other hidden BONUS DAMAGE, they're all minimal, irrelevant, until we get to the Spear-line VS Knight-line interaction. Then we can officially declare Sicilian Knight as the new baby Cataphract.It's massive, for comparison Cataphract blocks about 50% of Halb incoming bonus damage.So practically you need to upgrade your Pikes to Halbs when facing Sicilians just to have the same effect that Pikes have against normal Knights/Cavalier. (Civs with Halbs? Good luck)
*Camels actually now lose to Knights, only at Castle Age though.

I assume (hope) they dont have Hussars/Paladins. Which makes sense Historically. And highly to have no Plate Barding Armor. And Perhaps even Bloodlines, Very Cataphracty.

So so far we have 2 Civs that are highly encouraged to go pure Knight composition.

• Each Farm upgrade grants Farmers +1 carry capacity

And of course another meaningless Eco bonus, cause every civ needs an Eco bonus these days. (Hi Tatars)

• Serjeant: Infantry unit which can also construct Donjons

Krepost anyone? This Civ also clearly has no reasonable use of an Infantry addition in their Knight Composition, can only speculate about this venturesome concept. Perhaps this is what's going to save Sicilians from being 1 trick pony civ. (Burgundians)

• First Crusade: Upon researching, each Town Center spawns a one-time group of 7 Serjeants
• Scutage: Upon researching, each team member receives a one-time payment of 15 gold for each military unit that they own

Another niche doomsday rescue kit, however the combination between these two can be a bit scarry.