Somewhat inspired by this question: Can I use multiple hands for one attack, using this 6-Handed-Ones homebrew race?
As I started to explore with my question about playable Kuo-Toa, I'm interested in seeing what other humanoid monstrous races could be converted into playable races as per the monstrous races from Volo's Guide to Monsters? They've already got Orcs, Kobolds, Goblins, Hobgoblins, Bugbears and Yuan-Ti Purebloods, and now I've added Kuo-Toa (to my own personal library of playable races, I mean), but others that caught my eye included the Thri-kreen, an ant-like humanoid race with four arms (MM, p. 288).
At the time I steered away from them because of the multiple pairs of arms thing, but this "6-Handed-Ones homebrew race" question has inspired me to ask anyway; if I were to make, for example, a Thri-kreen playable race, what should I take into consideration with regards to the fact that they have four arms/hands?
What springs to mind is the fact that such a PC could potentially hold a shield, a greatsword and a spellcasting focus all at the same time, which seems quite powerful. Would a PC having multiple arms be inherently unbalanced due to such situations as this, or is there a way for such a racial trait to remain balanced in comparison to the existing playable races?
NB: There may be other concerns with converting Thri-kreen over to a playable race, such as the fact that they have strong natural armour providing a high base AC, poisonous bites, and the fluff text says they don't need sleep; I haven't begun to think about any of this yet because I stopped at this first hurdle - multiple pairs of arms. Hence I'd like answers to keep away from these other concerns and only focus on this one issue regarding multiple pairs of arms.