Difference between Unshakable and Ironclad

UNSHAKABLE vs IRONCLAD: NOUN

A naval vessel cased or covered wholly or partly with thick iron or steel plates, generally having a heavy backing of wood, so armored to resist projectiles or the attacks of rams or other armored vessels.
A 19th-century warship having sides armored with metal plates.
A naval vessel having the parts above water covered and protected by iron or steel usually in large plates closely joined and made sufficiently thick and strong to resist heavy shot. Modern naval vessels are made of steel throughout, and this term is only used in historical contexts.
A metal-plated ship, vessel, or vehicle
An armor-plated warship.
A wooden warship of the 19th century that is plated with iron or steel armor

Covered or cased with iron plates, as a vessel for naval warfare; armor-plated.
Noting an electrical apparatus or machine in which the iron part of the structure completely or partly surrounds and thereby mechanically protects the electric conductors: as, an iron-clad armature, one having the conductors embedded in slots or holes.
Figuratively, very rigid or strict; constructed, as a form of words, so as to allow no evasion or escape, or permit no flaw to be detected.

Unyielding, Unbreakable, Unshakeable, Incontestible, Firm, Watertight, Steady, Incontestable, Unassailable, Ironclad, Unbendable, Resolute, Unfaltering, Steadfast, Unwavering

Peremptory, Hard, Armored, Treaty, Mandatory, Rigorous, Stringent, Rigid, Brassbound, Incontestible, Inflexible, Incontestable, Unassailable, Watertight, Unshakable

Unyielding, Unbreakable, Unshakeable, Incontestible, Firm, Watertight, Steady, Incontestable, Unassailable, Ironclad, Unbendable, Resolute, Unfaltering, Steadfast, Unwavering

Peremptory, Hard, Armored, Treaty, Mandatory, Rigorous, Stringent, Rigid, Incontestible, Brassbound, Inflexible, Incontestable, Unassailable, Watertight, Unshakable

So no ironclad assurances can be made to the client.
And to make your case, you need ironclad arguments.
Customer need not download or even license Ironclad software.
Please note, however, that such privileges are not ironclad.
You have an ironclad firewall and antimalware system.
This falls somewhat short of an ironclad rule.
Ironclad Securitythemselves safe from a variety of threats.
Russian Technological Transfers: Naval Modernization and Ironclad Development.
Ironclad pitch excited Loughlin about leading the round.
There is no clear end to the ironclad period, but towards the end of the 1890s the term ironclad dropped out of use.