The hardest sword is not titanium sword from the vikings. It is the sword made of diamond.

or a sword with a diamond at the tip.

https://www.google.com/search?q=diamond+sword&rlz=1C1ASUT_enCA604CA604&espv=2&biw=1821&bih=774&site=webhp&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMIsYWlte6OyQIVApWICh3MpwwM&dpr=0.75#tbm=isch&q=+sword+made+of+diamond&imgrc=FYkMzU8b1OWDuM%3A