With Spiral Swords, bring them out, let them hit the enemy several times then change them to Blistering Swords for more damage, doing it this way will let you get the most damage out of them and will get back most of the DT you used to summon them in the first place. Personally I find Blistering Swords more helpful than Storm Swords in most circumstances, the main exception I can think of is in the Vergil Battles, you can use Storm Swords to destroy his Spiral Swords when he summons his when done correctly.
I would also recommend you try get all 3 hits of Judgement Cut down reasonably well, it's extremely helpful on VMD difficulty.
Stun locks not quite so sure what you what from this, as to whether you want it for bosses or normal enemies. Main one I can think of is Cerberus on DMD, there is a sort of stun lock loop you can get him into with Vergil, I did it on my Mission 3 SS run, I'll link it in here if you are interested. I didn't do it perfectly, but I got it pretty close.
You can still loop Geryon on VMD, same as you do with Dante basically.
For normal enemies I don't usually think about it much, but using your Spiral Swords with full out aggression tends to stun anyone who isn't in DT if that helps.
Also a little trick in case you didn't know, if you taunt while using Yamato as your weapon while in combat, you can fully restore your DT if you stay in his stance and don't get hit, is often easy to set up vs the basic level statues on Missions 7 and 13, for getting easy DT back for DTE etc. Usually you want to do it with a bit of a wall in the way to slow the enemies down as they try to get to you, can help if you really need DTE asap.
