@author = CE
currentInf = 'joint3'
currentSkin = 'skinCluster1'

sel = cmds.ls(sl=1, flatten=1)

def plusWeightFn1():
    cmds.undoInfo(openChunk=True, infinity=True)
    if currentInf:
        addVal = 0.1
        for v in sel:
            val = cmds.skinPercent(currentSkin, v, transform=currentInf, q=1)
            val += addVal
            cmds.skinPercent(currentSkin, v, tv=[str(currentInf), val])
    else: cmds.warning('[skinWrangler] No influences/joints selected')
    cmds.undoInfo(closeChunk=True)

def plusWeightFn2():
    cmds.undoInfo(openChunk=True, infinity=True)
    if currentInf:
        val = 0.1
        cmds.skinPercent(currentSkin, sel, tv=[str(currentInf), val], r=1)
    else: cmds.warning('[skinWrangler] No influences/joints selected')
    cmds.undoInfo(closeChunk=True)