Fel magic is a legal and accepted practice, particularly amongst the military branch of the Magisterium. They see it as a tool to be used in the defence of Silvermoon or a force to be subjugated, not as an unknown entity to be feared ot outlawed.
The “four laws of magic” are considered to be human superstition and fearmongering from particularly insular branches of the Church of the Holy Light, rather than a legitimate academic treatise. Mention them within earshot of a Magister and you can expect a lot of eye-rolling and debunking.*
Many blood elves remain in contact with relatives who became Forsaken. Whilst it hurts to be reminded of what they all once suffered, the fact that friends and relatives weren’t truly lost is a comfort to both sides during dark times.
All elves need a source of arcane magic; be it from managems and ley lines, to moonwells, to confluxes such as the Sunwell or well of eternity. Fel magic is a chaotic and potentially mutagenic alternative, given that it lies on the same cosmic axis.
Void elves are always hungering, or feel an emptiness where half of themselves used to be. Whilst the void sustains them, it’s only half of the great cosmic equation that spawned the cosmos. (and the arcane) Whilst they won’t starve and wither, they’re also not satiated either.
Presumably, the same thing would happen if an elf was lightforged, based on the same principle. Though rather than the whispers of the void, the all-consuming bliss of the Light would gloss over the hunger pangs.
There are a wide range of casting styles amongst elves, and magic is often woven into everyday life and the arts. An artist might channel mana into their tools, turning every brushstroke, carving, or musical note into a rune. A baker might use arcane dust in their pastries, creating delicate lattices of enchanted pastry that keeps the finished product warm and fresh for longer than mundane foods would. There are books that read themselves to the audience, and illustrations that move as the tales unfold.
Faith in the Holy Light is far more common In Quel’dorei than Sin’dorei, as the former have had more exposure to and are more welcoming of the Alliance – of which the Church of the Holy Light is far more widespread in, particularly with regards to humans and draenei. In Sin’dorei, the light is still largely seen as just another kind of magic, and the focus on the sun is based more on symbolism (in particular, defiance in the face of Elune’s priesthood) than belief.
Amongst older Thalassian elves, there’s a lot of antipathy towards the Kaldorei for exiling them after the War of the Ancients. Given that Lorash’s story revealed that he is old enough to remember the arrival in Tirisfal, it’s not hard to extrapolate that it’s still within living memory within Quel’thalas.
The exile of Umbric’s followers was controversial within Silvermoon, as all blood elves have dabbled in traditionally forbidden magic. As such, the move was considered hypocritical, and a number of magisters raised concerns that the administration might some day outlaw their research.
Quel’dorei tend to be more prone to illness and are more physically frail than their Sin’dorei cousins. Spending the years between the Fall and the Sunwell’s reignition with limited access to arcane magic took a severe toll on their health; and there were fatalities/witherings, particularly on those who were young or in ill health to begin with.**
Most sin’dorei paladins are blood knights, but not all blood knights are paladins. “Paladin” denotes a faithful warrior who lives and partakes in their particular religion, whilst the blood knight order was born of necessity; its methods involve draining light from an outside source (be it a relic, a naaru, or a sunwell) and using it much in the same way that a mage or warlock casts their spells. Whilst Liadrin might be swooning over the Naaru, that’s by no means a universal attitude.
“Honour” as humans or orcs know it, isn’t a priority or a value in Quel’thalas: after losing so much of their population, an “honourable death” is just another dead elf, and “honourable combat” is just giving your enemy a chance to kill more elves. Instead, Thalassian war doctrine focusses on guerilla tactics, avoiding direct confrontation, and ensuring that your foe is not going to get up again – and on intimidating any would-be threats into backing down.
The prevailing attitude to magic amongst Thalassian elves is that it is to be understood and mastered, not to be feared and shunned. This is due to the fact that their civilisation has been basking in and using it since long before the founding of Quel’thalas, rendering it a part of them rather than something external as it is for humans. Often, the attitude that magic is to be mastered is also applied to elements that are considered divine by other races
Likewise, all elves are capable of using it – though the actual level of skill still varies upon the individual. You can still have an inborn connection to the arcane and have all the proficiency of a potato.
An elf wholly drained of mana either withers or dies. Likewise, there’s no “cure” for the arcane hunger – it’s an environmental adaptation in the same way that a saltwater fish is able to thrive in saline conditions. To “cure” an elf would be to take away a fundamental part of them and turn them into something else entirely.***
Basic and utility spellcasting is part of the mandatory educational curriculum within Quel’thalas, much in the same way that IT lessons are now a mandatory part of schooling IRL. Magic is an everpresent force in Quel’thalas, much like technology is.