So when someone casts Shadow Blade - It summons a shadowy blade, etc., etc.
However, when the spell rolls - it's only applying a damage roll. It's not behaving like a standard "weapon" - where it's rolling a "to hit."
Is there something I am missing?
It's a weapon made from the spell. The weapon damage is based on the spell, it's quiet simple, and I use it on my warlock-rogue builds.
cast spell, have (insert flavor) shadowy swords in your hands you then treat it as a sword attack with a damage role based on the spell. As a rogue I still get the sneak attack, if the attack counts as a sneak attack. If you use it as a thrown weapon, it disperses at the end of the turn, but as a bonus action you can have it in your hands again on your next turn. In dark environments you get advantage on the attack which is good for the roguelock.
((Note I usually use it with my offhand, and never throw it. That way my main hand can be a rapier improved hex weapon.)
Oh, I get how the spell works. However, on D&D Beyond - there's no easy way to roll it.
So for example, the Rogue has dropped her dagger down a cliff side and has no short sword on their character sheet.
However, some enemies have jumped her - so she casts Shadow Blade and wants a sword.
Now, if she has no short sword on the character sheet - and the spell doesn't have it in there as "Roll Short Sword" and then it rolls the Short Sword Damage + 2D8 damage from the spell.
That's what I was trying to figure out an easy way of doing.
If you need a way to do this mechanically, make a homebrew item, simple enough, I've done that for psyblades and other things like that. Since while holding a Shadowblade in the off hand with a main hand weapon you count as dual welding for the feat and can get higher AC. But honestly I just manually roll it normally, it's not hard to roll a D20 and the modifier than roll the d8's and add dex, str, or chr if needed.
If you need a way to do this mechanically, make a homebrew item, simple enough, I've done that for psyblades and other things like that. Since while holding a Shadowblade in the off hand with a main hand weapon you count as dual welding for the feat and can get higher AC. But honestly I just manually roll it normally, it's not hard to roll a D20 and the modifier than roll the d8's and add dex, str, or chr if needed.