i design my sword based off of magik's soulsword from marvel's X-men her Sword is made out of her (you guess it) soul, it a weapon that is used to help magik uses spells and cut down powerful enemy. my design has energy around it enhancing the power it possess as well as contain it. 

Another character weapon i liked was Elsa from Elsword. Her fourth hero path Adrestia's sword was a nice design that i had to take insperation from and to gives slim look