I’ve noticed that ‘half casters’ such as the NightBlade and Gnomish Trickster start with 0 spells.
You could reason that you are rounding down 1/2 of 1 to 0.
But at every other odd level, they round up. So shouldn’t they be treated as level 1 casters at first? I know you include the odd bump in the math in the class creation rules… but why is it there at all?

+1. i never liked the fact that some casters cannot cast at level 1. I even give clerics one spell at level 1…what’s the purpose of being a spellcaster when not being able to cast a spell?

Player’s Companion rule:
Arcane 2: An Arcane Value of 2 gives the class the ability to casts spells and engage in magical research as a mage of ½ the character’s actual class level. After 1st level, round fractions of 0.5 or greater up. For instance, at 5th level, the character has the abilities of a 3rd level mage. The class uses its effective caster level (1/2 its level of experience) for purposes of level-dependent spell ranges, durations, and damage.
In general,t he intent is to reward mages and priestesses, and others who have spent enough build points to be “pure” casters, by giving them a spell at level 1 when other classes don’t get a spell until level 2.
It doesn’t break the game to give nightblades and clerics a spell at level 1, but it can influence class selection by players at the early game. A thief is less attractive if nightblade gets a spell at level 1, a priestess is less attractive if cleric gets a spell at level 1, and so on.
(And, yes, I know, the spellsword gets a spell at level 1. He pays for it in other ways, with a painful experience curve and steep level cap.)

Ah, ok I can kind of see that. Still not sure how I feel about it though, mostly from an aesthetic point of view.
Though for the record, I think the Spellsword pays for it directly! He is Mage 4 after all.

True, true. Don’t tell anyone, but I love Spellswords.