alright I had no plans to use White anyways. I was just adding in the Cannon abilitys.
I will look again at the effective areas etc and get back to you.
The show really again does not go into details. Tho I can check other sources.
oh wait this is what the Wiki has to say about her abilitys. I goofed a bit. (Info taken from RWBY wiki)
White - Weiss' default spell; this selection can create a solid-seeming force/energy disc that Pyrrha Nikos refers to as a "glyph", upon which she can stand, using it as a platform for various acrobatic movements including braking a free-fall and quickly reversing her motion by kicking off of it mid-air. When directly channeled through the blade, the white setting instead creates what is described as a 'finishing move' causing enormous damage to foes and potentially causing them to disintegrate into ice shards.
Yellow - Seems to enhance her agility. As of this time, we have not seen what happens if the yellow setting is channeled into a glyph.
Blue - When channeled into a glyph, this setting appears to create an anomalous gravitational field directly above the glyph. In the "White" Trailer, this is used to launch the Giant Armor in the air. In Players and Pieces, it enables Ruby Rose to ascend a vertical cliff-face as if she were running along the ground. It is also likely the setting that Weiss uses in the same episode to jump out of danger whilst carrying Nora Valkyrie. We have yet to see how this setting functions when used directly instead of through a glyph.
Red - When channeled into a glyph, this seems to create a repulsion effect. In the "White" Trailer, this is used to complete cancel out the force of one of the Giant Armor's sword strike. In Players and Pieces, it is used to boost Ruby Rose towards the Nevermore. In The Emerald Forest, this mode, when used directly, allowed Weiss to manipulate fire. Red runes appeared on the blade when she did this. This appears to be Weiss' primary ranged attack and is used again in Players and Pieces.
Light Blue - When used directly, this setting create a wave or field of ice, useful for trapping or immobilizing a foe. When channeled into Glyphs, it creates restraints that Weiss can launch towards a foe using a circling motion of Myrtenaster's blade.
Violet - This setting increases Weiss' attack power for a split second, dealing high damage with a slash attack. It is possible that this setting creates the black glyph that appears to have a motion-cancelling or adhesive effect that Weiss used to hold Ruby, in her makeshift slingshot, immobile until she had properly aimed her team-mate at the trapped Nevermore.
so as you can see some things are not explained. I am fine with rejection of some abilitys.