UngeheuerLich
Legend
If you replace PAM with warcaster it becomes mire or less the same.The difference is song of victory and the free hand.
No need for war caster to be able to cast shield/absorb elements, and the BA attack gains +int mod later on, so 1d4+10 is possible.
That isn't the same thing at all as an offhand shortsword.
Those few points of damage are more or less irrelevant at that point.
(we speak about 2d8+10 +1d4+10 vs 2d6+10 vs 1d6+5)
The difference is what you rate higher:
An extra attack of opportunity or the ability to use BB or GFB during an opportunity attack and advantage on concentration checks.
If you are set on using haste, I would really hate to lose concentration, because if you lose it, you have serious problems.