Vicious Ocean Tide Spear is comically bad compared to the other Event SSR Water weapons of very recent times (Water Sickle of Guilty Sloth, Lazy Bow Hail Punisher, and Rahab's Knife). Not only is the Spear incapable of being Full Limit Broken where the three aforementioned all can be, but its Assault is downgraded for Stinger which is pretty terrible Skill given that it requires both favourable element (which is the last element you'll need more damage against given that you already hit their weak point) and involves rolls for random spike damage rather than a steady reliable increase.
Against everything that isn't Fire, it has the same Weapon Skill as an SR except it demands way more fodder to increase. On top of all this, it inexplicably punishes you for using it as a Soul Weapon by hitting you with multiple debuffs upon Bursting.
I picked it up anyway because I'm new and still have some Level 85 SRs/Level 50 SSRs I can't break further that I need to replace, and the 40 extra Levels should be more than sufficient to offset the extra tedium of levelling its Blizzard Assault.
It's also a viable weapon to stuff in the grid just in case you pick up a phantom spear and you want to use it for your water team. Granted, that in itself is a stretch between the odds of picking up a phantom weapon and how few SSR water spears there are.
The weapon skill effect page putting crits in the same multiplier as berserk's pretty old. Like I remember that being the understanding last year.
Going through the history for the damage calculation page, it's the June 13 edit this year that put crits into their own multiplier. For that matter, the July 28 edit starts separating vigor from special (but still labeled both as special). The August 20 edit fully separates vigor from special.
On crit buffs, yes considering crit buffs are limited in time, so this pretty much skews the maths more towards nerf since you don't actually have infinite samples to work with, and tons more variability.
Spreading consistently is a thing that applies to stinger, and even then, stinger's not exactly the first weapon skill that comes to your mind when you think a good grid.