It all depends on what Royal Guard your making, for example a Bruiser Royal Guard has no use for skills such as sacrifice and doesn't need Battle Chant because Inspiration is pretty much an offensive version of Battle Chant, and the points are better spent on spear quicken and spear mastery for damage output. Spear Quicken increases Overbrand damage significantly and Overbrand level Increases Moonslasher damage significantly, so basically I would max out all three of those skills if your going for Overbrand. I would also use Exceed Break with Overbrand because Vellum Glaive and Hunting spear are really heavy and will give extremely good damage output with Exceed Break.
However Overbrand is not the only means for leveling even though it's definitely the most popular, you can also use Cannon Spear, which is really good with 120 str paired up with an Imperial Spear or the weapon Cannon Spear. I would also use Vanishing point, Shield Press and Earth Drive with Cannon Spear because Imperial Spear plus Imperial Shield combo will give crazy damage output for all four of those skills.
Cavalier Mastery increases your aspd when on a mount and is pretty much a must with any build since Vanishing Point and Exceed Break are ASPD based, but if your making a tank then no you can ditch it. Also if your using Rapid Smiting plus Gloomy Shyness then you won't need a mount in general because Gloomy forces you off your mount.
The only time you wouldn't get Inspiration is if you go Banding instead, Inspiration is for a lone wolf Royal Guard play style, while Banding is a pack mentality skill path. People are always concerned about the exp penalty for using Inspiration, but that's normally because they don't know how to properly recharge it using spare card and a slotted foot gear with an exp bonus card such as an Am Mut card. Banding of course also has it's draw backs since you need 7 royal guards to unleash it's true potential, or at least one other Royal Guard who also has banding to even use the skill.