The degree of an element $x$ in a Lie algebra or an Ext-algebra is the first degree of the homogeneous element $x$. The zero element has degree 0; however, its degree should be thought of as arbitrary. The degree of a Lie derivation $d$ is the first degree of $d$ considered as a graded map.
i1 : L = lieAlgebra({a,b,c},Weights=>{1,2,3})
o1 = L
o1 : LieAlgebra
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i2 : firstDegree(c a b+a b c)
o2 = 6
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i3 : E = extAlgebra(5,L)
o3 = E
o3 : ExtAlgebra
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i4 : apply(gens E,firstDegree)
o4 = {1, 2, 3}
o4 : List
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i5 : d=lieDerivation({a c b,b b c,c c b})
o5 = d
o5 : LieDerivation
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i6 : firstDegree d
o6 = 5
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