Sorcerrer Crit Damage bonus gloves

Maligaro's Virtuosity, Fine Bracers‌ I use these gloves and when I press G I can see that I have 300% crit dmg bonus under the spell I use, but then the guide tells me to take several extra crit dmg bonus nodes in the passive tree but each time I take 1 the 300% remains under G in the spell book, is this a visual bug why else would the guide say to keep taking crit dmg bonus nodes?

"Your critacal damage bonus is 300% "
Its fixed on 300, cant increase or lower.

As noted above, this Unique's ability simple sets your Critical Bonus to 300%. It cannot be changed from there. This item is a way to cheat into a pretty high Critical Bonus without needing to invest skills or other items into it.

As to why a guide might suggest this, either the writers are bad at reading, or those nodes are being taken for a secondary reason (i.e the notable has a different valuable effect, like Critical Chance).