I haven't read everyone else's reply, so I may be repeating things here ...
In terms of game mechanics, khopesh is the superior weapon, especially versus single target mobs, which is what this build will likely be doing a lot of.
However, I would recommend stick with bastard sword for the following reasons:
1. You will continue to enjoy going out of sale prices on any bs you need to fill in your collection (improved cursespewers, disruptors, smiters, etc) ... for a player new to the game I consider this significant. Everyone likes to feel rich and in DDO you will feel rich if you invest your plat in bs'es - you can proudly boast about the +3 improved cs bs of shattermantle or +3 bs of gcb you scammed off AH for 10Kpp ea and all the khopesh users will be groaning.
2. You can save the khopeshes you loot for your next DPS build which will use khopeshes. Attractive TWF khopesh builds these days include stuff like 2 monk 6 pally 12 fighter or reverse the ftr and pally.
3. bs's and dwa's have glancing blow - not sure how the mechanics will play out, but bs's are being brought back from the grave given this little boost from the dev's.
4. the tier 1 ingredients you used will be meaningless after you run Shroud about 10 more x. That does not mean it was a waste, it means it is basically meaningless. What is less meaningless is the fecundity ingredients you used to craft the blank, IMO. Because some of those are expensive - since no one likes to run Coal Chamber.
5. Doing something different is cool.
6. There is a very interesting epic bs you can eventually obtain, which appears to rival some tier 3 shroud weapons. True, it will grant you bs proficiency, but it will not grant you the ftr & kensai bs enhancements you already have invested, so this will be an interesting weapon in the hands of your build. Here is the weapon of which I speak: http://ddowiki.com/page/Epic_Chimera%27s_Fang. That lightning strike is I believe the same lightning strike (500-700 dmg) that you obtain with tier 3 shroud weapons, a very popular choice like mineral 2. To take full advantage of this weapon, you need to be human and have greater mark of siberys sentinel.
7. A guy on our server named Panekiller uses bastard swords - on several toons (or used to). I think at one time maybe 10-15 folks in our guild (GSI) were giving Pane all their high end bastard swords - because they knew he used them and they knew they wouldn't. So if you get into a decent raiding guild and develop a rep as a nice guy, you become the recipient of everyone's bs's - for FREE!!!!