At first, Infernoble Knights do not seem directly related to the original archetype. Their effects pertain mostly to FIRE Warrior-type monsters. However, they can benefit the old build by increasing the number of extenders available, give utility effects, and open up new combo trees.
Extenders
Infernoble Knight - Olivier and Infernoble Knight - Renaud act as both a Warrior extender for Isolde, Two Tales of the Noble Knights, and as a Level one Tuner for Infernoble Knight Vanguard - Roland. These two are what connects the old and new - namely, in their ability to enable viable Synchro summoning.
Olivier's condition may seem costly to meet, but you can often send a Noble Arms card that outlived its purpose. For example, a Noble Arms equip spell attached to Noble Knight Borz is going to be sent to the GY after using Borz for a Link Summon. Olivier's protective effect is the most useful to tutor for Charlemagne but otherwise provides protection for any Warrior-type.
Renaud's condition may suggest that it only belongs in a pure Infernoble Knight deck. The factor that bridges the old knights with Renaud is Isolde - as long as you can access Isolde, you can summon Renaud. His recursion effect is useful for both recovery and combos. Combined with Isolde, Renaud can tutor any Equip spell! A popular choice is Living Fossil, which combined with a Level four monster is a recipe for summoning Infernoble Knight Emperor - Charlemagne. Just remember, Renaud needs to summon itself by its own effect to gain Tuner status!
Utility
Infernoble Knight Ogier is not impactful on its own. But he has utility as a Fire Warrior-type when you need to summon one with Isolde to fulfill Renaud's condition. In that case, Ogier can send Until Noble Arms Are Needed Once Again or Gwenhwyfar, Queen of Noble Arms if you could not resolve Noble Knight Borz this turn. Its protective effect as an Equip spell isn't a slouch either - it is useful to block popular removal such as Interrupted Kaiju Slumber and Lightning Storm.
Infernoble Knight - Maugis is similar to Noble Knight Brothers in concept. Combining the two provides Noble Knight with an unparalleled level of resources. Noble Arms - Excaliburn and Until Noble Arms are Needed Once Again become fuel for Maguis' effect. Once Maugis is in the GY, his recursion becomes a free draw each turn! His protection is weak compared to Ogier and Olivier, but can help stall decks without removal.
Infernoble Arms - Durendal is straightforward consistency. There isn't much to say except that it increases the chance of a full combo by searching Renaud. While simple, it is incredibly effective! Please note that Durandal does not need a Warrior-Type to activate.
Infernoble Arms - Hauteclere is a more traditional Noble Arms. Combined with Noble Arms - Clarent and Gallatin, Hauteclere increases Noble Knight's OTK capabilities. Furthermore, by equipping it to Noble Knight Artorigus, Hauteclere complicates an already puzzle-like scenario by providing destruction on Artorigus' removal.
Synchro Capabilities
Infernoble Knight Vanguard Roland is a Tuner Synchro, a stepping stone to Charlemagne. There are only benefits from climbing up from Roland! While you may have already used Isolde to send Smoke Grenade of the Thief or Noble Arms - Excaliburn to the GY, you may have used Maugis or Brothers to send them back to the Deck. In that case, Roland can send them again and provide an extender for the next turn. Noble Knight Medraut, God Phoenix Gearfried, or Renaud - Noble Knights are not hurting for extenders.
Roland synergizes well with Charlemagne with its quick GY effect. By combining the two, Charlemagne becomes a 3500 ATK Zoodiac Drident.
Speaking of which, Infernoble Knight Emperor Charlemagne ties together the archetype. If you go first, Charlemagne combos with Isolde to equip Smoke Grenade of the Thief and punctures the opponent's hand. Otherwise, he can pick and choose his forms of protection. This all snowballs if he is left on the field - his equip effect works on the opponent's End Phase as well.
Old Knights with New Purpose
Due to the awesome consistency Durendal provides, any card that can tutor Equip spells also tutors Fire Warrior monsters. Ignoble Knight of High Laundsallyn's effect essentially searches Renaud, with the potential to mold your hand if it can run over a monster.
Glory of the Noble Knights wasn't great before, but now functions as a tutor spell for Infernoble Knights! It can also provide any other Noble Arms in niche situations, or proc the effect of Noble Knight Drystan.
Conclusion
By providing Tuners and Synchros, Infernoble Knights became a compact way to change the Noble Knight playstyle. While it can be used as a pure deck, combining both styles' capabilities makes for a deck that can gain massive advantage, oppress the opponent, and OTK with flair.
