While Shuumatsu no Izetta takes place in an alternate history, many real-world World War II-era weapons and vehicles are featured in the anime, as well as a few weapons unique to the world of the anime, though many of them have clear real-world influences.
The Eylstadt Army use a Modele 1935 pistol as a standard issue sidearm. Given that the real-world Modele 1935 is a French design, its seems plausible that this is Thermidorian import.
Tobias uses a Walther PPK in the first episode to defend Ortfiné Fredericka von Eylstadt from Germanian agents. The Walther is a small semi-automatic 7.65mm pistol designed for police use. Ironically, the weapon may in fact be made in Germania, given the real-world PPK's German manufacture, as well as the fact that Germanians are seen using the Walther P38.
The standard rifle of the Eylstadt Army is a MAS-36, a bolt-action rifle. The real-world MAS-36 was made in France, suggesting the rifles may have been imported from Thermidor
Suppressed Sniper Rifle
The Royal Guard of Eylstadt are seen using a suppressed sniper rifle in the elaborate ruse to disguise the geographic limitations of Izetta's powers. While remarkably quiet and equipped with a telescopic sight, the rifle is a single shot weapon with no magazine. The rifle does not appear to be a real-world weapon, suggesting it may be manufactured in Eylstadt. Alternatively, the weapon may be some form of air rifle.
The Eylstadt Army use the Hotchkiss M1909 as their standard light machine gun. The Hotchkiss is clip-fed weapon, meaning it has a much lower rate of fire than the belt-fed Germanian MG-34. The weapon is typically operated by a crew of two, one firing and one loading the weapon, though it could be used by one man in an emergency, as Jonas proved during the Battle of Coenenberg. Given the real-world Hotchkiss' French origins, the Hotchkiss seen in the anime may be a Thermidorian import.
Eylstadt Anti-Tank Rifle
The Eylstadt Army used an anti-tank rifle possibly of Eylstadtian manufacture at the Battle of Coeneberg. The weapon is later commandeered by Izetta, who uses it both as a mount and for its intended purpose as an anti-tank weapon, at one point using her magic to hyper-accelerate a round and completely overpenetrate a Germanian Panzer.
Izetta's Anti-Tank Rifle
Starting with her official introduction as Eylstadt's super-weapon, Izetta was given a custom-made anti-tank rifle as both a weapon and mount. The rifle resembles a real-world British Boys .55 or Finnish Lahti L-39. The weapon has a large bore, perhaps firing a round as large as 20mm, and is equipped with a number of custom features, including handlebars equipped with a trigger for firing while Izetta is riding it, as well as a motorcycle-like seat.
The Renault FT, known after World War I as the Renault FT-17 was the first tank designed with a revolving turret, a feature which revolutionized tank design. In real life, the tank was designed and manufactured in France, suggesting that, like much of Elystadt's weapons, it is Thermidorian import. The Renault could be armed with either a 37mm light cannon or a machine gun, though all tanks in Eylstadtian service were armed with the cannon. During the BattleS of Coenenberg and the Sellun corridor, multiple Eylstadt FT-17s were annihilated by German Panzers without a single kill, demonstrating the obsolescence of the tank.
The Morane-Saulnier M.S.406 is the primary fighter aircraft of the Eylstadt Air Force, and is seen in multiple scenes, often flying or fighting alongside Izetta herself, the also play the role of "supply plane" for Izetta, like carrying swords. In real life, the M.S.406 was manufactured in France, suggesting the M.S.406s in the anime are imported from Thermidor. The M.S.406 was highly maneuverable and decently armed with a 20mm automatic cannon and two 7.5mm machine guns, however, in Eylstadt (as they were in real-world France), the M.S.406 was slower and not as well armed as the Me-109s that were their main adversary. The Germanian aircraft also heavily outnumber the Eylstadt Air Force.
"Twin" M.S. 406
The Eylstadt Air Force also operates a two-seater heavy fighter consisting of two M.S. 406 fuselages connected by a shared central wing in a manner similar to the real-world F-82 Twin Mustang. It is likely that the aircraft is faster than the standard M.S. 406, given the two engines, and more heavily armed, having at least two 20mm cannon (one in each fuselage) and possibly two extra machine guns in the shared wing.
After Izetta's use of medieval lances and swords as projectiles at the Battle of Coenenberg, Izetta was given specialized projectiles which resembled medieval lances, presumably for psychological purposes. While outwardly similar to lances, these projectiles had a hardened steel tip capable of penetrating the upper rear armor of a Panzer IV, and a follow-through explosive charge designed to detonate about a second after the lance embeds itself in the target. Izetta was able to use her powers to guide the lances to their targets like a missile.
250kg Glide Bomb
After her use of torpedoes in a manner similar to real-world anti-ship missiles to sink the German carrier Drachenfels, the Eylstadtian military developed a winged glide bomb with a 250 kilogram high explosive warhead based on standard bombs used by the Eylstadt Air Force. The weapon was intended to use the weapon as heavy air-to-ground missile guided by her magic, intended to allow her to destroy multiple tanks or other ground targets at once.
Mauser Kar. 98K
Flakpanzer IV Wirbelwind
The Messerschmitt Me-109 is the primary fighter aircraft of the Germanian Air Force. The fighter is, like it's real-life counterpart, capable of competing against any Allied fighter in the early period of the war, being armed with two 13mm machine guns and a 20mm cannon, and having a top speed of 640 kilometers per hour. Against a target as small and maneuverable as Izetta, the Me-109 had difficulty getting a clear shot at.
One of the partially complete aircraft in development at the Germanian R&D facility appears a Horten Ho-229 jet fighter-bomber. The real Ho-229 was a prototype flying wing aircraft armed with two 30mm cannon and a small bomb load, intended initially as a high-speed light bomber, with the cannons later added to allow it to act as a fighter. The appearance of the Ho-229 is anachronistic, having not actually been designed until 1943, having first flown in 1944 and never seen combat.
Aircraft Carrier Graf Zeppelin "Drachenfels"
The aircraft carrier "Drachenfels" appears to be a real-world Graf Zeppelin-class aircraft carrier, which was slated to carry 43 aircraft, including 20 torpedo bombers, 13 dive bombers, and ten fighters, with a total length of 262.5 meters. The carrier also carried a large compliment of naval guns for surface combat, a feature not found on carriers of other nations. In real life, none of the Graf Zeppelin-class were completed, suffering from constant delays due to political issues. The completion of Drachenfels suggests differing priorities in the Germanian Navy compared to real-world Nazi Germany. The Drachenfels, once completed, was deployed in a fjord in Germanian occupied Nord, where it could threaten Allied shipping while remaining safe from the more powerful Britannian Navy. The Drachenfels was destroyed by Izetta during an operation in which she was deployed along with four torpedoes from an Avro Lancaster bomber. After the initial plan to launch the torpedoes at the bilge failed, Izetta used the levitated torpedoes similar to real-life anti-ship missiles, disabling the flight deck elevator before levitating a second torpedo into the hole in the deck, where it struck the fuel tank. The resulting explosion sunk the ship.
The Germanians use dozens of winged rockets similar to the real world V-1 rocket to attack Landsbruck after their breakthrough at the Sellun Corridor. Sophie used her magic to guide the weapons with pin-point accuracy from long distance, essentially using them similarly to real-world cruise missiles. The rocket attack destroyed all of the anti-aircraft batteries in Landsbruck, allowing Germanian transport planes to drop paratroopers unopposed. One rocket also hit the Palace, and rockets may have struck other targets in Landsbruck as well.