[NEW MERCENARIES] Please note that all new forum users have to be approved before posting. This process can take up to 24 hours, and we appreciate your patience.
Actually, yes you may revert the item to the original appearance. You'll need x1 Regular Weapon Fusion Rune and x1 Premium Weapon Fusion Rune; both can be purchased off the Marketplace via Airtight.
First, you'll want to purchase a low lvl bastard sword and a terminus sentinel bastard sword (not the one you have at the moment)
Next, you'll fuse the low lvl bastard sword with the regular Weapon Fusion Rune to the terminus bastard sword that you got off the marketplace (again, NOT the one that is currently fused to Lvl 70 weapon)
Then, you'll use the Premium Weapon Fusion Rune and fuse your Terminus to the low lvl weapon that looks like a Terminus Bastard Sword
Voila! There you have it. :-)