[quote=@UltikanaRe]
<Snipped quote by IncredibleBee>

Normal is a stretch. Yes, this shows it is possible, and I might let you use a utility knife instead of a shield seeing that video, but I see no reason from the evidence presented too allow it to do more damage. 
Also, high fantasy just means a lot of magic. A lot of different varieties of DnD worlds exist, some low-fantasy with gritty realism and rare spell casting with long rests needed alongside painstakingly crafted and gathered materials to produce simple effects, others with high fantasy magic sword shops. Regardless of this, unless you want to use a warp physics spell, the rules for dual wielding will be removed. 
[/quote]

Not only is it possible, that very video displays some of the advantages to be had from using a parrying dagger of some kind. In Japan, you also have Miyamoto Musashi, arguably the country's most famous martial artist, and he's known for developing a two sword style.

Also, all spells warp physics by their very definition.