[Vrul]

Try:

local _, class = UnitClass("player")
if class ~= "ROGUE" and class ~= "SHAMAN" then return end

local addonName = ...
local tooltip = CreateFrame("GameTooltip", addonName .. "TempEnchantScanner", UIParent, "GameTooltipTemplate")
tooltip:Hide()

local tempEnchants
if class == "ROGUE" then
    tempEnchants = {
        ["Mind-Numbing Poison"] = GetSpellTexture(5761),
        ["Crippling Poison"]    = GetSpellTexture(3408),
        ["Paralytic Poison"]    = GetSpellTexture(108215),
        ["Leeching Poison"]     = GetSpellTexture(108211),
        ["Deadly Poison"]       = GetSpellTexture(2823),
        ["Wound Poison"]        = GetSpellTexture(8679),
    }
elseif class == "SHAMAN" then
    tempEnchants = {
        ["Earthliving"] = GetSpellTexture(51730),
        ["Flametongue"] = GetSpellTexture(8024),
        ["Frostbrand"]  = GetSpellTexture(8033),
        ["Rockbiter"]   = GetSpellTexture(8017),
        ["Windfury"]    = GetSpellTexture(8232),
    }
end

local tooltipLine = addonName .. "TempEnchantScannerTextLeft"
tooltip:SetScript("OnTooltipSetItem", function(self)
    for lineNum = 1, self:NumLines() do
        local texture = tempEnchants[_G[tooltipLine .. lineNum]:GetText():match("^(.+) %(")]
        if texture then
            self.texture = texture
            return
        end
    end
    self.texture = nil
end)

hooksecurefunc("TemporaryEnchantFrame_Update", function(_, mainhand, _, _, offhand)
    if mainhand then
        tooltip:SetInventoryItem("player", 16)
        mainhand = tooltip.texture
    end
    if offhand then
        tooltip:SetInventoryItem("player", 17)
        offhand = tooltip.texture
    end
    if mainhand then
        if offhand then
            TempEnchant2Icon:SetTexture(mainhand)
            TempEnchant1Icon:SetTexture(offhand)
        else
            TempEnchant1Icon:SetTexture(mainhand)
        end
    elseif offhand then
        TempEnchant1Icon:SetTexture(offhand)
    end
end)