I recommend this for any bst, your DoT increases greatly. Won't increase spike damage in rampage, but you sure will be doing more rampages. Also as BST you should have no problem farming stones for yourself.
BST can equip Ridill, but really shouldn't. It's not at all comparable to a WAR using one, you're lacking quite some skill and aggressor. This weapon is BST's only chance to catch up with a dual wielding WAR; A- skill multi-hit weapon for singlewielding or offhanding when /NIN.
I just got one of these last week after wanting it for the longest time.
The wait was worth it, TP gain using this is fast. It's especially nice when paired with Primal Rend and a ws macro that contains a lot of CHR and MAB.