The word howitzer (referring to a type of cannon) was first borrowed into the English language in a 1695 edition of the London Gazette, where it was spelled hauwitzer. Throughout the 1700s, it was occassionally also spelled hautvitzer, hautwitzer, hawitzer, hawbitzer, hobitzer, and haubitzer, until the modern form became standardized in the nineteenth century. The word comes from German Haubitze, which is from the Czech word houfnice, meaning "catapult" (this term was introduced to the Germans during the Hussite Wars in the 1400s). -Nice served as a nominal suffix; the root is houf, which usually would translate to "crowd" but here meant "heap" (as in the catapult's payload). Ultimately, that traces to Proto-Germanic haupaz and Proto-Indo-European hupo, with the same definitions.

An egg cream is a kind of sugary dessert drink that contains neither eggs nor cream. The cream part exists because it's based on a more expensive version of the beverage that did contain cream, but for egg we'll have to dig deeper, to its origins in the Ashekenazi Jewish community in New York City. One theory is that it's actually a corruption of the Yiddish word echt, meaning "genuine" or in this case something more along the lines of "good". That would trace to German echt, which translates to "real" and derives from Proto-Germanic aiwaz ("long time") and Proto-Indo-European hoyu. Alternatively, it could also be because it's modelled on a drink that did include egg yolks; both explanations are unconfirmed.  We do know for sure, though, that after its first attestation in 1841, literary usage of the term skyrocketed, peaking in 2004.

The melody from eeny meeny miny mo is ubiquitous. It shows up as eena meena ming mong in Zimbabwe, une mine mane mo in France, and takes many other forms in a myriad of cultures. Nobody knows exactly where it comes from - linguists have postulated that it's everything from a corruption of Dutch to creole spoken by African slaves - but the most credible theory I've seen on this was proposed by Princeton lecturer Adrienne Raphel back in 2016. Apparently, it may trace to a rhyming counting system used by northern English shepherds that went yan, tan, tethera, methera, pimp and was eventually also the basis for other rhymes such as hickory dickory dock. Nonsense words were substituted, but the tune remained the same. Unfortunately, the second part of the rhyme most schoolchildren learned today, catch a tiger by the toe/if he hollers let him go, used to be catch a Negro by the toe/if he hollers make him pay (or that with the n-word), in reference to the punishment that escaped slaves would receive when caught. This was eventually whitewashed with more innocent lyrics, but received renewed publicity when a Southwest Airlines stewardess used the cleaner rhyme on a 2004 flight, which upset an elderly Black passenger so much that she had a seizure and sued (she eventually lost). The Wikipedia page on this, this article about the court case, and this article on racist children's songs are good for further reading if you're interested.

When the word strategy was first used in a 1616 translation of a Greek military text, it was a noun referring to the office of a general or commander. Later, it came to be metonymically applied to the plans and operations carried out by those offices, and by the late 1880s it was used in non-military contexts as well. It was borrowed from the Ancient Greek word strategos, meaning "general". That's composed of stratos, which meant "army" (but literally translates to "that which is spread out", from Proto-Indo-European stere, "spread"), and agos, meaning "leader" (traces to the Proto-Indo-European reconstruction ag, "to drive" or "draw forward"). Stratos is also the source of stratosphere and agein composes parts of glucagon, pedagogue, synagogue, agony, and many other words.

The word spruce was first borrowed into Middle English in 1378 with the spelling sprwys. Back then, it meant "of or pertaining to Prussia", because the tree was traditionally associated with the country. That's an alteration of Prus, the Old French name for for Prussia, but nobody is completely certain why the s got added the the beginning of the word. The only theory I see out there is that it got conflated with spruse, a generic term for commodities traded by Hanseatic merchants that also existed around the time. It's no coincidence that the word Prussia sounds like Russia; both it and Prus come from the Proto-Slavic root Po-Rus, meaning "before the Rus" people who went on to found Russia. Beyond that, there are no Indo-European reconstructions; seems like everything about this word is shrouded in intriguing obscurity.

The word pistol​ was borrowed in the 1560s from Middle French pistole, which is thought to derive from the Czech word pištala​, which described a specific type of hand-cannon that they used in the 1400s. Pištala could also mean "tube" or "pipe", but it most literally translates to "whistle", because the objects were thought to have a similar shape (as a speaker of Serbo-Croatian, I notice that the verb for "whistling", pištanje, is also related). That derives from Proto-Slavic piskati, meaning "squeak" or "whistle", and ultimately is onomatopoeic of the sound of whistling. Since reaching widespread usage in the late eighteenth century, usage of the word pistol has been fairly constant. The verb pistol-whip was first recorded in 1942 and pistol-butt is from 1914.