Being that soul annihilation is a primary attack and not a full attack I'd prefer 2 hander. My goal was to experience a single class cipher. Ascendant looked good on paper but I found you don't get enough casts off while ascended. The mechanic didn't feel pleasing to me. Beguiler looks very good but the lack of guides and need to go ranged made me want to try soul blade first. I want to experience tier 8 and 9 abilities and hope that a few of them work well with soul blade. My fear is having base con and tanked resilience would make me useless. So stat spread is in question. As is full build really (items. Abilities at each level etc)  has anyone made this work and had fun with it? Any tips would be lovely.  Thanks kindly

Soul annhilation is added damages, so it doesn't really matter what style you use, Soul Annhilation would buff your attacks about equally.

However, as a Single Class Cipher, you may want to use Time Parasite to buff your attack speed so much that other attack speed buffs (such as dual wielding ones) become irrelevant. So I think Two hander would be the best Style in this case.

Why do you say that Beguiler has to go ranged ?

It just seems like it should being that it'll do a lot more casting and gain focus from hitting deceived enemies with more deception. Do you think t8/9 is really worth it for a 2handed soul blade to not go multiclass? I really like the idea of coming into some really cool top tier powers in the end, I've played builds that bloom early (paladin/rogue multi'd with other classes) and it doesn't suit me. But if it's really not worth it I may do something like soul blade/devoted (even though it REALLY sucks that soul annihilation doesn't proc mob stance when you kill with it. bs imo). 

I'd go multi-class. Single puts you in an odd position where casting reduces your SA effectiveness, and beyond that there's not much to do beyond SA and auto attacks.