It is driven by a few things. First, Germany has a long standing, codified govt policy of not delivering arms to conflict zones unless it has a formal security agreement with such a country, mainly through NATO. This, of course, arises out of German post-WW2 pacifism.
Secondly, there are historical complexities within the German identity of doing anything that can be seen as fomenting/contributing to war in that particular stretch of land. The German psyche simply does not want to be involved in this, as in the German mind, the area between the Dnieper and Stalingrad WAS World War 2. That is what the German mind immediately goes to when that conflict is brought up…it isn’t D-Day, it isn’t the Western Front, it isn’t the fall of Berlin, it isn’t the Nazi occupation of Western Europe…it is fighting Russians within the space between those two geographic points that is where the complete trajectory of the German existence changed. So even on top of a relatively “peacenik” culture, the geographic history there is one of high significance.
Thirdly, the Germans do not view the Ukrainians as allies. This is a misconception in the US. They view Ukraine as a source of massive corruption, immeasurable chaos, unpredictable, and essentially merely a “friend-of-a-friend”, with the common friend being the US. I am being quite literal when I say that literally every single summit, supportive statement, transfer of billions of Euros from the Germans to the Ukrainians is done out of one, single consideration and that is as a nod to the relationship with the US, which the Germans do value. The average German citizen, the German state, and German industry want nothing to do with Ukraine in any way whatsoever. Germany will kill any effort whatsoever to integrate the Ukrainians into either EU or NATO.
Fourthly, it would go a long way in pushing Germany into an actively adverse camp from Russia, which is not want Germany wants. German sees this event as fleeting and that good, productive, profitable relations with Russia will pick up where they left off once this dies down. By actively arming Ukraine, that becomes much more difficult from a PR perspective.
And finally - and this is a very, very sensitive point both within Germany - the images of German weaponry in the hands of certain Ukrainian front-line troops will be a public relations disaster here that no government here will be able to withstand. The background here is simple…a significant percentage (but by no means a majority) of the most effective fighting forces on the Ukrainian side are open neo-nazis. This fact is massively overstated and exploited in propaganda by the Russians, but it is also significantly downplayed by the Americans and Brits and in related English-language media coverage.
Specifically re the Azov Battalion, although there are others, which is a very large conglomeration of very effective troops numbers estimated now to be the size of two brigades, is one of the most effective fighting forces in Ukraine, and many of its members are openly Neo-nazi. A couple of years ago they were officially absorbed as a distinct unit within the larger Ukrainian military, but they have a high degree of continued autonomy and even with all their ideological transgressions, the Ukrainian military would be at a huge disadvantage without them. They are particularly effective military units.
But, that said, Azov fights officially under the Banner of the Wolfsangel, which is a nazi symbol that is illegal in Germany. They march annually commemorating the 14th Waffen Grenadier Division of the SS, they are adorned with Nazi regalia, they venerate Nazi-Collaborator Stepan Bandera, and they are vocal in their affinity for many tenets of National Socialism. Their ex-leader/political head, Andriy Biletsky, who was actually the former Deputy of the Ukrainian parliament AFTER the war which made him famous as a neo-nazi, and still commands significant influence in the Ukrainian Right has even talked about their duty being “to lead the White races of the world against a final crusade against the Semite-led untermenschen.” So basically, this is a very effective fighting group made up of some very, very bad people. The Guardian had an article just after the war in 2014 about how much of a connundrum this is for the Ukrainians:
https://www.theguardian.com/world/2014/sep/10/azov-far-right-fighters-ukraine-neo-nazis
In fact, the German Ambassador to Ukraine even had to issue a formal statement last April condemning the Ukrainians for continuing to allow marches commemorating the SS Galicia, particularly since those marches had reached Kiev (they used to just occur in the west of Ukraine, such as Lviv). The highly influential German public broadcaster, ZDF, ran stories on primetime here about how significant Neo-Nazism was in Azov Battalion and a few other special forces units, and they posted pictures of these battalions wearing SS regalia, adorning their military gear with the Swastika, Totenkopf, SS runes, Wolfangel, etc.
The Canadians are dealing with their own scandal relating to this right now, in fact, and as you can see in the Ottowa Post, the scandal is not ONLY that NATO advisors were knowingly training Neo-nazis, it is that THEY KNEW about it over a year before meeting with them and were actively trying to find ways to keep it from the press as part of their plans in lead-up to the meeting. You will also see images in both articles that come from some of the TV programs put out by German public broadcaster, ZDF. I don't want to post them myself, as that shit can get dicey here.
https://nationalpost.com/news/national/10-3-podcast-canadian-officials-under-fire-after-meeting-with-ukrainian-battalion-unit-linked-to-neo-nazis
https://ottawacitizen.com/news/national/defence-watch/canadian-officials-who-met-with-ukrainian-unit-linked-to-neo-nazis-feared-exposure-by-news-media-documents
Even American politicians like the late John Conyers and current rep Ro Khanna have raised serious concerns about this. The truth is that probably no more than 15% of the overall Ukrainian army are Neo-nazis, but a significant percentage of the most effective elements of the Ukrainian forces are. The JPost article I posted below gets into this in depth, and addresses the Simon Wiesenthal Center's deep concerns over this.
I do want to note that I am somewhat uncomfortable getting into this, as it is frequently exploited by Russians to broadly condemn the entirety of the Ukrainian military as Neo-nazis, so I will leave some reputable, familiar American links below to explain some of this in better detail. And I am not saying that the Russians are correct here by any means in asserting that this is all of the Ukrainian’s viewpoint…but it is certainly there and it is known by the Germans. The Nation article is very well-sourced and particularly damning.
Ukraine's Neo-Nazi Problem: https://www.reuters.com/article/us-cohen-ukraine-commentary-idUSKBN1GV2TY
https://www.jpost.com/Diaspora/US-lifts-ban-on-funding-neo-Nazi-Ukrainian-militia-441884
https://www.thenation.com/article/archive/neo-nazis-far-right-ukraine/ https://www.jta.org/2018/04/29/global/nazi-symbols-salutes-display-ukrainian-nationalist-march
There are endless reports of this. You can take from it what you like, and I am not going to argue about how widespread this ideology really is, but in all honesty, the Germans are very, very uncomfortable with this. Not only because of the geo-strategic issues relating to Russia that I touched on above, but because anyone who actually follows this understands that it is not just a possibility, but a probability, that Ukraine collapses internally in the very near future given the external pressures, resulting in some kind of civil war...and what will the Germans be seen to have done? Armed Neo-Nazis who turn weapons on other Ukrainians. To the Germans, this is a powder keg where they can easily envision news stories of civil war in Ukraine, with neo-nazis holding freshly produced German weapons. Not good, Bob. Not good.
I mentioned in an earlier post that I frequently visit the cemetery of my wife's family to tend to traditional, German customary duties towards dead relatives' graves. Well, one side of the family is buried about 50 yards from the above referenced Nazi-Collaborator Stepan Bandera in one of the most idyllic well-known cemeteries in town. The grave is CONSTANTLY adorned by Ukrainian nationalists with imagery that is illegal under the German Strafgesetzbuch (prohibition on Nazi imagery) and the cemetery authorities have to come out weekly to clean it all up. Every, single, week. It is awful. But my point in saying that is that the correlation between the Ukrainians and that ideology is not a huge stretch for the Germans, because, frankly, they see it themselves in graffiti and news stories. In fact, you will sometimes hear, "and what when this falls into the hands of the Banderites?"...it is a real consideration here.
And, in my opinion, if the US starts to push too hard on this the Germans will start to run english-language stories in the media pointing this out to take the heat off. The only reason they haven’t specifically mentioned this is out of deference to the US, but the groundwork is already laid domestically. The Germans know that this element is significant in certain pockets of the Ukrainian forces.